The Quran

وَإِذ تَقولُ لِلَّذي أَنعَمَ اللَّهُ عَلَيهِ وَأَنعَمتَ عَلَيهِ أَمسِك عَلَيكَ زَوجَكَ وَاتَّقِ اللَّهَ وَتُخفي في نَفسِكَ مَا اللَّهُ مُبديهِ وَتَخشَى النّاسَ وَاللَّهُ أَحَقُّ أَن تَخشاهُ ۖ فَلَمّا قَضىٰ زَيدٌ مِنها وَطَرًا زَوَّجناكَها لِكَي لا يَكونَ عَلَى المُؤمِنينَ حَرَجٌ في أَزواجِ أَدعِيائِهِم إِذا قَضَوا مِنهُنَّ وَطَرًا ۚ وَكانَ أَمرُ اللَّهِ مَفعولًا

Ali Unal

(Remember) when you (O Messenger) said to him whom God has favored (with guidance to Islam and close companionship with the Prophet), and whom you have favored (with kind treatment, special consideration, and emancipation): “Retain your wife in marriage and fear God (concerning your treatment of her).” You were hiding within yourself what God (had already decreed and) would certainly bring to light: you were feeling apprehensive of people (that they might react in a way harmful to their faith), while God has a greater right that you should fear Him (lest you err in the implementation of His commands). So, when Zayd had come to the end of his union with her (and she had completed her period of waiting after the divorce), We united you with her in marriage, so that there should be no blame (or legal impediment) for the believers in respect of (their marrying) the wives of those whom they called their sons (though they really were not), when the latter have come to the end of their union with them. And God’s command must be fulfilled.¹

The Messenger’s actions and norms of conduct constitute, like his sayings, the second source of the Islamic Law or constitution. His Companions inherited and transmitted whatever they observed while he was living among them, while his wives narrated and conveyed the rules and norms of the Islamic personal and family life. This heavy responsibility required that he should have wives of different temperaments, upbringing, and character. A great many of the religious matters and rules were narrated by these women, known as the Pure Wives.
Zayd ibn Hārithah was the Messenger’s emancipated slave and servant, whom he called “my son,” according to the customs of the time before adoption was legally abolished. The Messenger, upon him be peace and blessings, had requested that Zaynab bint Jahsh, a “noble-born” lady from the Messenger’s clan, be married to this former slave to show in action that people should not judge others by their color or social status. However, their marriage did not last long. Zayd, realizing his wife’s sublime character, admitted that he was spiritually and intellectually inferior to her. So, he eventually divorced her. As stated in: We united you with her in marriage, God ordered His Messenger, upon him be peace and blessings, to marry Zaynab. This was extremely difficult for the Messenger, uponhim be peace and blessings, to do, because according to the prevailing customs, “adopted” children were treated as if they were real children, and Zayd, as mentioned above, was his emancipated slave and servant. But God willed that this custom be abolished and first put it into effect through His Messenger, upon him be peace and blessings. The Messenger, upon him be peace and blessings, apprehended that the people might draw incorrect conclusions and think unbecoming things about him if he were to perform such an action, and this would, therefore, harm their faith. But such a grounded “legal” fiction was to be eternally abolished, and God willed that such an established custom be abolished through His Messenger’s actions, because only then would it be able to have the desired effect upon the people. So, the Messenger, upon him be peace and blessings, had no alternative other than to obey God’s decree, as he always did.