Urwah bin Zubair (may Allah have mercy on him) narrated that Abu Hudhaifah bin Utbah bin Rabi’ah (may Allah be pleased with him) was among the companions of the Prophet ﷺ, and he participated in the Battle of Badr. He had adopted Salim as his son, who was called “Salim, the freed slave of Abu Hudhaifah.” Just as the Messenger of Allah ﷺ had adopted Zaid bin Harithah (may Allah be pleased with him) as a son. Since Abu Hudhaifah (may Allah be pleased with him) considered Salim his son, he married him to his niece Fatimah bint Walid bin Utbah, who was among the first to migrate and at that time was one of the most distinguished unmarried women of the Quraysh. Then, when Allah the Exalted revealed in the Qur’an regarding Zaid bin Harithah (may Allah be pleased with him): “Call them by (the names of) their (real) fathers; that is more just in the sight of Allah. But if you do not know their fathers, then they are your brothers in religion” (Al-Ahzab: 5), everyone returned their adopted sons to their real fathers. Whoever’s father was not known was attributed to their emancipators. After this, Abu Hudhaifah’s (may Allah be pleased with him) wife, Sahla bint Suhail (may Allah be pleased with her), who was from the Banu Amir bin Lu’ayy tribe, came to the Messenger of Allah ﷺ and said: “O Messenger of Allah ﷺ! We used to consider Salim as our son, and he comes and goes to me while I am in simple home clothing, and our house is one. What do you say about him?” The Prophet ﷺ said: “The ruling regarding what has reached us is that you should give him five breastfeedings, and he will become unlawful for you (as a foster son) through that milk.” She did so, and she considered Salim her foster son. Umm al-Mu’minin Aisha (may Allah be pleased with her) deduced from this that if she wished for a man to be able to come to her, she would order her sister Umm Kulthum and her nieces to breastfeed him (even in adulthood), and then he would come and go to her. All the other wives of the Prophet ﷺ rejected this, saying: “In our opinion, the ruling that the Messenger of Allah ﷺ gave to Sahla bint Suhail was a special concession only for Salim (may Allah be pleased with him). No one can come to us through such breastfeeding.” This is the matter in which there was a difference among the wives of the Prophet ﷺ regarding the breastfeeding of an adult.
Hadith Referenceمسند الإمام الشافعي / كتاب النكاح / 1190
Hadith Takhrijاخرجه البخارى النكاح، باب الأكفاء في الدين (5088) - (4000)۔