This topic will be split into three parts:
1) The first will deal with the allegation levelled at Muhammad that he married his daughter in law
2) The second will deal with the allegation that he lusted after her whilst she was married to his adopted son
3) The third and final part will sumarise the main points
1)Did Prophet Muhammad peace be upon him really marry his daughter in law?
It is quite ironic that the haters of Islam try with their best attempts to discredit the True and Wonderful Religion of Allah Almighty, Islam, even if it were a lie and they knew that it was a lie.
One of the constant points that are usually brought up by the anti-Islamics against our beloved Prophet peace be upon him and Islam is the one where Muhammad married his adopted son's wife after they got divorced.
According to the Western culture, an adopted son becomes an actual son. But this law does not exist in Islam.
Let us look at Noble Verses 33:4-5 "Allah has not Made for any man two hearts in his (one) body: nor has He made your wives whom ye divorce by Zihar your mothers: nor has He Made your adopted sons your sons. Such is (only) your (manner of) speech by your mouths. But Allah Tells (you) the Truth, and He Shows the (right) Way."
Zihar is the divorce done by pagan Arabs before Islam, where a man would say to his wife you are to me like my mother. The man could marry another woman, where the woman couldn't marry another man, which was very degrading to all women.
Zayd's, the Prophet's alleged "adopted son" by the haters of Islam, wife, was the one who wanted to divorce him and marry the Prophet. She was not forced into the marriage by any means. Let us look at Noble Verse 58:1 "God has indeed heard (and accepted) the statement of the woman who pleads with thee concerning her husband and carries her complaint (in prayer) to God: and God (always) hears the arguments between both sides among you: for God hears and sees (all things)."
Let us look at Noble Verse 33:37 "Behold! thou didst say to one who had received the grace of Allah and thy favour: 'Retain thou (in wedlock) thy wife, and fear Allah.' But thou didst hide in thy heart that which Allah was about to make manifest: thou didst fear the people, but it is more fitting that thou shouldst fear Allah. Then Zayd had dissolved (his marriage) with her, with the necessary (formality), we joined her in marriage to thee: In order that (in future) there may be no difficulty to the believers in (the matter) of marriage with the wives of their adopted sons, when the latter have dissolved with the necessary (formality) (their marriage) with them. And Allah's command must be fulfilled."
According to Islamic laws, where from the above Noble Verses do we see our beloved Prophet Muhammad peace be upon him marrying his daughter in law?!
According to Noble Verses 33:4-5 above, we clearly see that an adopted son is NOT in the place of an actual son. An adopted son is a son from a stranger person. The foster father would still have to treat the adopted son with kindness and fulfill all of his needs. But the adopted son can never be an actual son.
According to Noble Verse 33:37 above, we clearly see that Allah Almighty allowed for the Muslims to marry the former wives of their adopted sons!.
If a man called another's son "his son", it might create complications with natural and normal relationships if taken too literally. The truth is the truth and can not be altered by men's adopting "sons". "Adoption" in the technical sense is not allowed in Muslim Law. Those who have been "wives of your sons proceeding from your loins" are within the Prohibited Degrees of marriage, but this does not apply to "adopted" sons; "Prohibited to you (for marriage) are your mothers, daughters, sisters; father's sisters, mother's sisters; brother's daughters, sister's daughters; foster-mothers (who gave you suck), foster-sisters; your wives' mothers; your step-daughters under your guardianship, born of your wives to whom ye have gone in no prohibition if ye have not gone in (those who have been) wives of your sons proceeding from your loins; and two sisters in wedlock at one and the same time, except for what is past for Allah is Oft-Forgiving, Most Merciful. (The Noble Quran, 4:23)"
Prophet Muhammad peace be upon him did not marry his daughter in law as the deceivers from the anti-Islamics always claim. Prophet Muhammad peace be upon him is a Great Messenger from Allah Almighty. Allah Almighty in the Noble Quran does not recognize an adopted son as a real son, because He, the Almighty, has His Great Wisdom behind it, to save us from complications such as genetical testing and cultural/social problems that may arise from one discovering the true identity of his father. This is something that should not be hidden from a child.
The Narratives Concerning The Marriage of Zaynab To The Prophet (P)
It was by Allah’s Will that Zayd ibn Haritha divorced his wife when it was no longer possible for them to live together. At the same time, it is also a part of human nature to find difficulty to abandon what one has been brought up to believe in, i.e. adoption. Adoption is not a social rule that could be conquered easily nor could its effects upon society quickly perish.
One of the most important effects produced by adoption upon society was that the foster father was not entitled to marry his foster childs former wife. When Islam arrived, it banned adoption and with it its impact upon social norms. And for this mission, Allah had chosen the Prophet Muhammad(P) and He ordered him to marry Zaynab bint Jahsh(R) after her divorce from his former foster son, Zayd.
Muhammad’s (P) marriage to Zaynab had sent the unbelievers and hypocrites to criticise this marriage, for they say: “Muhammad married his foster-son’s former wife out of lust”! So did the Orientalists of the last century, the most notorious of them being William Muir and D.S. Margoliuth. They have taken advantage of this marriage by accusing the Prophet Muhammad(P) of “conveniently” using the Quran to legitimize this marriage and subsequently questioned his Prophethood.
Our purpose now is to challenge these false accusations. And as this is a sensitive and serious issue, since it directly concerns the most honorable of All?s creatures, we will view the narrations of this story that these Orientalists have built their case upon. I will also point out the criticism that was directed to some parts of the narration chain, and to the narration itself by respectable Islamic scholars.
Circumstances of the Divorce
“Behold! Thou didst say to one who had received the grades of Allah and thy favour: Retain thou (in wedlock) thy wife, and fear Allah. But thou didst hide in thy heart that which Allah was about to make manifest: thou didst fear the people, but it is more fitting that thou shouldst. Fear Allah. Then when Zayd had dissolved (his marriage) with her we join her in marriage to thee: in order that (in the future) there may be no difficulty to the believers in (the matter of) marriage with the wives of their adopted sons, when the latter have dissolved (their marriage) with them. And Allah’s command must be fulfilled.” (Holy Quraan, 33:37)
The main reason behind the divorce of Zayd and Zaynab was the problems that arouse throughout their marriage. Therefore, Zayd divorced her by his own will though the Prophet(P) prohibited him from doing so. At the same time, the Prophet(P) knew what was going to happen, and that the divorce was to be, but he concealed it from people fearing that they might say: He married the former wife of who was called to him as a son. 
The sum of everything that reached us regarding this divorce — which has been used to claim that there was another motive behind this divorce — is that Muhammad(P) happened to see Zaynab by accident, which lead her love “to fall into his heart”. And as he was leaving he made a remark that indicated his admiration for her. Therefore, when Zayd heard that, he was determined to divorce Zaynab and sacrifice his wife for the Prophet’s(P) desire and passion. It is also mentioned that Zayd consulted Muhammad(P) in this matter, and that the Prophet(P) advised him not to — though he secretly wanted this divorce to befall Zaynab in order to marry her afterwards. Above all, the Prophet(P) admitted that, and Allah even scolded him for trying to hide what he knew was to happen.
Despite the ugliness and viciousness of these narrations and despite this understanding of the verse that mentioned this incident, some of our honorable scholars have taken by these narrations, such as:
• Ibn Jarir in his book Jami-ul-Bayan (22/12)
• Ar-Razi in his book (13/184)
• Ibn Al-Qayyim in his book Al-Jawab Al-Kafi (p. 247)
• Az-Zamakhshari (3/262)
The best excuse we might find for these scholars and their followers is that they have considered it a symptom of human nature, like any other sign of anger or happiness. Yet, they have not realized the ugliness of such narrations being ascribed to the Prophet(P) nor have they examined the chain of these narrations carefully. Therefore, we ask Allah to forgive them.
Criticism of the Chain of Narrations
We begin by critically analyzing the reports involved via its isnad (chain of narration), as follows:
It was mentioned by Ibn Saad in his Tabaqat (8/101), and also Ibn Jarir in his Tarikh (3/161). They said:
Muhammad Ibn ‘Umar said: ‘Abdullah ibn ‘Amr Al-Aslami said: Muhammad Ibn Yahya Ibn Habban said: the Prophet(P) came to Zayd Ibn Haritha?s house asking for him - when Zayd was called Muhammad’s son. When the Prophet(P) wanted him he asked: where is Zayd? Then he went seeking him at his house. But he didn’t find him at home, accordingly, Zaynab came out to receive him, wearing her nightgown. The Prophet(P) turned his face, and she said: He isn’t here O Prophet of Allah, but I beg of you to come in. but the Prophet(P) refused to. She came out in her nightgown for she hurried when she was told that the Prophet(P) was at the door. She fell into the Prophet’s heart, then he left murmuring incomprehensible words, except for: Grace be to Him Who directs the heart. When Zayd came home, Zaynab told him that the Prophet(P) had been at their house. Zayd asked her: Did you not tell him to come in?! Zaynab said: I have but he refused. Zayd asked: did he not say anything? Zaynab said: he left murmuring something I couldn?t understand, but I heard him say “Grace be to Him Who directs the heart?. Afterwards, Zayd went to the Prophet(P) and said: O Prophet of Allah, I have been told that you have been to my house, and that you have refused to come in. if it had been that you like Zaynab, I shall leave her for your sake. But the Prophet(P) said: Hold on to you wife. But Zayd couldn’t live on with Zaynab from that day. He would come to the Prophet(P) and ask him again, but the Prophet(P) would say: Hold on to your wife. And Zayd asked him again, and the Prophet(P) would still say: Hold on to your wife. But Zayd divorced Zaynab and her period was over. Meanwhile, the Prophet(P) was talking to ?Aisha when all of the sudden he was addressed by the Holy Spirit. He was relieved, and said smiling: who shall go to Zaynab and tell her that Allah has make her my wife? Then he recited the verse “Behold! Thou didst say to one who had received the grades of Allah and thy favour…” to the end of it.
The first flaw regarding this narration is that it is mursal (i.e., two reporters are missing), because Muhammad ibn Yahya ibn Haban was not a Successor, he narrated from the Companions and the Successors such as ‘Umar Ibn Salim and Al-A’raj, etc. He died 121 A.H. when he was 74 years old, so he did not witness the incident, nor had he mentioned who had he taken the narration from. 
The second flaw is that Abdullah ibn ‘Amr Al-Aslami is agreed upon his weakness (in narration). Moreover, Al-Bukh said about him: “his narration is to be ignored”. And Abu Hatim said: “abandoned”. 
The third flaw is that Muhammd ibn ‘Umar is Al-Waqidi, a storyteller who has many narrations, but they are dropped from consideration. Furthermore, some scholars accused him of lying and fabricating hadith. 
It is mentioned in Ibn Jarir’s Tafsir (22/13), he said:
Yunis told me: Ibn Wahab said: Ibn Zayd said: The Prophet(P) wedded Zayd bin Haritha to his cousin Zaynab bint Jahsh. On the day the Prophet (pbuh) went out in search of him (Zayd), the door of his house was but a piece of fabric, therefore the wind blew it open and revealed Zaynab (with her sleeves up). And she fell into the Prophet’s(P) heart, and since then she hated the other (Zayd). Then Zayd came to the Prophet(P) and said: O Prophet of Allah, I want to leave my wife. He said: Why? Do you have any suspicion about her? He answered: No! by Allah I have no suspicion about her and I have seen but goodness from her. Then the Prophet(P) said: Hold on to your wife, and fear Allah in her. For that is what Allah said: “Behold! Thou didst say to one who had received the grades of Allah and thy favour: ‘Retain thou (in wedlock) thy wife, and fear Allah.’ But thou didst hide in thy heart that which Allah was about to make manifest” i.e., hide in thy heart that if you leave her I will marry her.
It is mu’dil (i.e., more than two reporters are missing), for ibn Zayd (who is Abdur-Rahman ibn Zayd ibn Aslam), is neither a Companion nor a Successor, and accordingly two or more narrators are absent.
Abdur-Rahaman Ibn Zayd Ibn Aslam is weak by the agreement of Hadith scholars, and some went as far as to say that his narrations are to be abandoned. Al-Bukhari and Abu Hatim said:
Ali Ibn Al-Madini considered him very weak. It is reported that Ash-Shaf?i said: Abdur-Rahman Ibn Zayd Ibn Aslam was asked, “Did your father told you on authority of your grandfather that Allah’s Messenger (pbuh) said: Nuh’s Ark circumambulated the (Sacred) House and prayed behind the Maqam two Rak’aas” he answered, “Yes”. That is why when an interrupted Hadith was narrated to Malik, he said: Go to Abdur-Rahman Ibn Zayd to tell you on authority of his father about Nuh. Statements of Imams regarding his weakness are so many. He was a good man deep in the soul, but he was so much involved into praying and worship that he could not memorize Hadith, so he was considered weak. 
Some tafsir is related from him, if it is of his own opinion in understanding the Qur’an, it is evaluated. If it related on authority of others, it is unacceptable, let alone being without isnad!
It is mentioned in Ahmad’s Musnad (3/149-150), he said:
Mu?mil ibn Ismail told us: Hammad ibn Zayd said: Anas said: The Prophet (pbuh) came to Zayd bin Haritha’s house, and saw his wife Zaynab. He might have entered their house (I am not sure whether it is Hammad?s comment or originally in the Hadith). Then Zayd came to complain to the Prophet (pbuh) about her, but the Prophet (pbuh) said: Hold on to your wife and fear Allah, then the verse “and fear Allah.” But thou didst hide in thy heart that which Allah was about to make manifest? was revealed till “we join her in marriage to thee”, i.e., Zaynab.
Some of the scholars strengthened Mu’mail’s narrations, but the majority agreed that he is weak and narrates denounced reports. Yaqoub Ibn Sufyan said:
His narrations are not similar to his colleagues’ and scholars should revise his narrations for he narrates denounced reports on authority of trustworthy narrators, which is yet even worse, for if he had narrated denounced reports on authority of weak narrators he might have had an excuse.
Muhammad ibn Nasr Al-Marwazi said about Muamail:
If he was the only narrator of some narration, this narration should be delineated and thoroughly examined, for he lacked strong memory and frequently made mistakes. 
Some trustworthy narrators from Hammad’s companions had narrated this report, however they did not mentioned the first part. They only mention the part where Zayd complained to the Prophet(P) and the Revelation of verses. 
It is mentioned by Ibn Jarir in his Tafsir (22/13), he said:
Bishr told us: Yazid told us: Sa’eed narrated from Qatada: Behold! Thou didst say to one who had received the grades of Allah which is Zayd whom Allah had blessed with Islam. and thy favour:, who was liberated from slavery by the Prophet (pbuh). Retain thou (in wedlock) thy wife, and fear Allah.”, the Prophet (pbuh) concealed his wish that they shall be divorced. Al-Hasan said: There never was a verse severer on him than But thou didst hide in thy heart that which Allah was about to make manifest? If Allah’s Prophet (pbuh) was to conceal any part of revelation, he would conceal this thou didst fear the people, but it is more fitting that thou shouldst. Fear Allah. The Prophet (pbuh) feared what people might say.
Abdur-Raziq narrated from Mu’mmar from Qatada this story briefly, he said:
Zayd Ibn Haritha came and said: O Prophet of Allah, Zaynab’s language with me has grown tough, and I wish to divorce her. But the Prophet (pbuh) told him: Fear Allah, and hold on to your wife. At the same time, the Prophet (pbuh) wished that he would divorce her but he also feared what people might say. 
Qutada is Ibn Duama As-Sudousi and one of Imam memorizers, well-known for his Tafsir, whatever he interprets according to his understanding of verse, is evaluated. As for his narrations, it is only taken when the whole chain of narrators is mentioned, provided direct hearing is stated. But in this case, the narration is mursal and reporters after him are not mentioned, so it is considered very weak.
Qatada was unable to differentiate(between authentic and unauthentic reports). Abu ‘Umar Ibn Al-’Alaa said about him: Qutada and ‘Amr Ibn Shu’aib used to take narrations from everybody, nothing they considered false.
Even though his understanding and explanation for the verse is not so detailed as others, we can still interpret them in light of other authentic narrations by saying that the words “wish” or “love” meant that the Prophet(P) knew that Zayd would divorce her, and he only feared that people would think of Zayd as his son even after Allah had banned adoption, and they might say that he had married his son’s former wife.
Al-Qurtubi mentioned it in his Tafsir (14/190):
Muqatil said: The Prophet (pbuh) wedded Zaynab bint Jahsh to Zayd, therefore she lived with him for a while. One day the Prophet (pbuh) came calling on Zayd, and he saw her standing before him. She was white, and one of the finest women in Quraish, therefore she fell into the Prophet?s heart then he left saying: Glory be to Him Who directs the heart. Zaynab heared that and told Zayd about what she had heard. Zayd understood, so he went to the Prophet (pbuh) and said: O Prophet of Allah, allow me to divorce her, she has this air of arrogance, which is greater than what I can endure, and her language also hurts me! But the Prophet (pbuh) said: Hold on to your wife, and fear Allah in her.? It was also said that wind blew into the fabric which served as a door - and lifted it, which accidentally exposed Zaynab to the Prophet (pbuh) and he saw her, as a result she fell into his heart. Zaynab knew that and told Zayd when he came back. Right then, Zayd decided to divorce her.
This narrations chain of reporters was never mentioned all the way to Muqatil. And even if it was authentic up to Muqatil, it would be still of no value for he is Muqatil ibn Sulaiman and is not given credit by most scholars, he was also acused of fabricating narrations and criticized his Tafsir.
Ibn Ishaq said:
Zayd was ill, therefore the Prophet (pbuh) went to visit him. Zaynab Zayd’s wife - was at his head nursing him. Just as she left to do something, the Prophet (pbuh) looked at her, lowered his head and said: Glory be to him ho directs hearts and eyes. Then Zayd said: shall I divorce her for you O Allah’s Messenger? But the Prophet (pbuh) said: NO. Then the verse Behold! Thou didst say to one who had received the grades of Allah and thy favour: Retain thou (in wedlock) thy wife, and fear allah was revealed.
This report’s chain of narrators was not mentioned and we did not find it in Sirat Ibn Hisham.
Criticism of The Text
We have previously discussed the weakness of these narrations by the unreliability of their isnads. Now let us look at them in regard to their matns (i.e., texts). Here we attempt discuss the texts of the narration and show the problems inherent within it.
1st perspective: The contradictions these narrations hold. In some of them it was said that the Prophet(P) came to visit Zayd, but Zayd was not home before the Prophet(P) was received by Zaynab. While other narrations state that Zayd was ill, therefore the Prophet(P) went to see him. So, Zayd, Zaynab and the Prophet(P) were all at the same room. How could Zayd be away and ill in bed at the same time?
2nd perspective: The narrators differ in narrating the state and the way in which the Prophet(P) saw Zaynab; some said he was at the door, others say she came out, while others say he saw her when the wind blew the fabric barrier.
3rd perspective: All the narrations agree that when the Prophet(P) saw Zaynab, she “fell into his heart”. But this “love” they speak about came too late (after her marriage) which is absurd and ridiculous, for Zaynab was born when the Prophet(P) was then 12 years old and she grew up with him as his cousin. Did he not recognize her beauty until after her marriage to Zayd Until then, the hijab was not an obligation; hence he must have seen her without it. And if the allegations that he had loved her were true, he would have married her himself instead of wedded her to Zayd.
4th perspective: If we make the assumption that Prophet(P) fell in love with her after seeing her as Zayd’s wife, how could one do what the Prophet(P) had done ? whether it was what he said or lowering his head - how could that have indicated his assumed love to Zaynab or even Zayd Besides, the Prophet(P) prohibited a man from loving or wanting another man’s wife, would it possible for him to go against his own prohibition? Even if we assume that the Prophet(P) showed his assumed attraction accidentally and that he was acting spontaneously, how did the narrator decide that in his heart he(P) was determined that Zayd must divorce her from his own sake?
Above all, how would Allah then scold him for hiding his love for Zaynab and for hiding his wish that she shall be divorced? Imagining this is enough to prove the falsehood of these narrations.
5th perspective: These narrations were used to explain the verse and even if there were no other narrations, it isn’t proper to use these ones for explaining Allah’s Book, for they have been proven false by both isnad (chain of reporters) and matn (text). In the same time, there are other narrations which are qualified to be used , neither problematic nor denounced; what the Prophet(P) hid was what Allah had informed him regarding his marriage with Zaynab and what he feared was people saying that he married his son’s former wife. Strangely enough, some commentators forsake these fault-free authentic narrations and mentioned the abnormal eccentric ones.
After proving these narrations faulty and false regarding both isnad and matn, of notable interest is the position that some investigative scholars had firmly stood in opposition to these false narrations; some mentioned and refuted them and some ignored them.
After a summarizing these narrations and showing the sinlessness of the Prophet(P) , Ibn Al-’Arabi said: “All these narrations’ chains are not to be considered.”
After mentioning the right explanation of what the Prophet(P) hid and what he feared, Al Qurtubi said: “This is the best interpretation of the verse and it is the position of investigating scholars and commentators like Az-Zuhri, Al-Qadi Bakr Ibn Al-Alaa Al-Qushairi, Al-Qadi Abu Bakr Ibn Al-Arabi and other. As for what has been narrated about the Prophet(P) and his love for Zaynab - and some may use the word “adore” - this have not come but from a person who is unaware of the Prophet’s sinlessness or of his rank.”
After mentioning the authentic narrations, Ibn Kathir said: “Abu Hatim and Ibn Jarir mentioned here some narrations from some Salaf that we ignored due to their lack of authenticity. Imam Ahmad also related a strange narration by Hammad Ibn Zayd from Thabit from Anas which we also ignored”.
After mentioning the authentic narrations, Ibn Hajar noted: “There are other narrations related by Ibn Jarir and Ibn Abi Hatim and transmitted by many commentators that should not occupy our minds”.
A great number of Islamic scholars nowadays paid attention to such narrations and realized their harmful effect and implication in regard to the rank of Prophethood, so All?enlightened their hearts to expose these intruding narrations and awaken the Islamic Thought to confront any trial to undermine the status of Allah’s Messenger(P) or to distort the historical facts in Islamic heritage.
Sheikh Muhammah Rashid Reda said:
Storyteller has — regarding this event — some sayings that should not be accepted and we should keep the Prophet (P) away from such nonsense falsely attributed to him.
The Prophet’s (P) marriage from Zaynab bint Jahsy was at the middle of Dhul-Qai’dah, 5 H. when she was 35 years old.
Al-Bukhari related in his Sahih, that Zayd came complaining of his wife. The Prophet(P) kept saying: “Fear Allah and hold on to your wife”. ‘Aisha said: “If Allah’s Messenger were to hide something, he would hide this one. She [Zaynab] used to express pride before the wives of the Prophet (P) and say: Your parents wedded you and Allah has wedded me above Seven Heavens.”
Even if allegations of the anti-islamists were true it would not detract from the veracity of the prophet. Muslims admit that he was a human being. It is not unnatural for a man to fall in love. The fact that he is a prophet does not rob him of his natural human emotions. In fact it is true that he loved his wives.
However, it is not true that he fell in love with Zainab in the way that is claimed by some critics. They say that once the prophet visited Zaid, the husband of Zainab. Zaid was out at the time, and Zainab was combing her hair. The prophet was struck by her beauty and immediately left saying something to the effect that God changes the hearts of people. When Zaid learnt about this incident he offered the prophet that he would divorce Zainab in order that the prophet may marry her. Accordingly, he divorced her and the prophet married her.
Several things point to the lack of truth in this story. First, it is unlikely that the prophet (pbuh) was suddenly struck by Zainab's beauty. Zainab was his cousin. He had known her since childhood. Why would she suddenly appear striking after she was already married to another?
Second, the prophet had arranged for her to get married to Zaid. If there was to be an attraction why did the prophet (pbuh) not encourage her to marry none but himself?
Third, the fact of the matter was that Zaid's marriage proved to be an unhappy one. Zaid was a former slave and as such was held in low esteem in the eyes of Zainab. He mentioned to the prophet that he intended to divorce his wife. But the prophet advised him to keep his wife and avoid divorce.
In the meantime, Zaid intended to divorce his wife, Allah intended to marry her to the prophet. Eventually Zaid could maintain his marriage no longer. He divorced Zainab and Allah declared in his Glorious Book that he has wedded her to the prophet after the proper waiting period was over.
This marriage served more than one purpose. First, the prophet was responsible for arranging Zainab's marriage to Zaid. In a sense, then, he was also indirectly responsible for the unhappiness she felt in her marriage. Her marriage to the prophet now provided her the honour she felt she deserved, and exonerated the prophet.
Second, Zaid had been adopted as the prophet's son. Eventually, however, the Qur'an prohibited the practice of changing the parental identity of adopted persons. Zaid, then, was to no longer be called "son of Muhammad" but rather "a close friend." The prophet's marriage to the divorced wife of Zaid was a practical demonstration that the adopted relationship was not equal to a real blood-relationship. A man cannot marry the divorced wife of his real son but he can marry the divorced wife of his adopted son.
The abolishment of the age-old practice was a positive improvement for the adopted persons. People outside of Islam still continue this practice for their own benefit. They adopt children and rob them of their real identify, making them believe they are real children of the household in which they grow up. When such children realize the truth they suffer much disappointment and grief. The adoptive process continues for the selfish gain of the adoptive parents.
But is it not true that children sometimes need adoptive parents? Yes. But they also need to preserve their real identify. This is what Islam ensures. It is the responsibility of the entire community to help children in need. They should be taken in and nurtured but not confused with one's own children.
The prophet's marriage to Zainab was a bold measure to forever engrave in the minds of his followers that as much as people would resist change, some changes are worth the effort. Adoptive children should no longer be robbed of their real identities. We should not forget that every action of a prophet is for a reason, and is designed to teach us a lesson and to bring about a positive change - as it did in this situation.
 Cf. Tabari, Jami’-ul-Bayan (22/11). Ibn Kathir, Tafsir Al-Qur’an Al-’Azim (3/489). Al-Bukhari, Sahih, n. 478
 Cf. At-Tahzib (9/507-508)
 Cf. At-Tahzib (5/275), Mizan Al-I’tidal (2/448)
 Cf. Mizan Al-I’tidal (3/664)
 Cf. Al-Tahzib (6/178)
 Cf. At-Tahzib (10/381)
 Cf. Al-Bukhari, n. 7420. At-Tirmithi, n. 3212. An-Nisa’i, n. 11407
 Cf. Fath Al-Bari (8/524)
 Cf. At-Tahzib (8/301-305)
 Cf. At-Tahzib (10/274-275)
 Cf. General Ahmad Abdul-Wahhab, Ta’adud Nisa’ Al-Anbiyaa wa Makanat Al-Mar’ah fi Al-Yahodiyyah wa Al-Masihiyyah wa Al-Islam, p. 68.
 Cf. Ibn Al-Arabi, Ahkam Al-Qur’an (3/1543)
 Cf. Sunan Abu Dawud, n. 5170.
 Cf. Ibn Al-’Arabi, Ahkam Al-Quran (3/1543)
 Cf. Al-Qurtubi, Al-Jami’a Le Ahkam Al-Quran 14/191.
 Cf. Ibn Kathir, Tafsir Al-Qur’an Al-’Azim 3/491
 Ibn Hajar, Fath Al-Bari 8/524
 Cf. Rashid Reda, Muhammad Rasoul Allah, p. 275
 Ibn Saad, At-Tabaqat (8/114)
 Sahih, n. 7420