Narrated Aishah, Ummul Muminin: The Prophet ﷺ said: What is unlawful by reason of consanguinity is unlawful by reason of fosterage.

Umm Salamah reported Umm Habibah said “Are you interested in my sister, Messenger of Allah ﷺ?” He said “What should I do?” She said “You marry her” He said “Your sister?” She said “Yes”. He said “Do you like that?” she said “I am not alone with you of those who share me in this good, my sister is most to my liking. He said “She is not lawful for me. ” She said “By Allaah, I was told that you were going to betroth with you Darrah to Durrah, the narrator Zuhair doubted the daughter of Abu Salamah. He said “The daughter of Umm Salamah? She said “Yes”. He said “ (She is my step daughter). Even if she had not been my step daughter under my protection, she would not have been lawful for me. She is my foster niece (daughter of my brother by fosterage). Thuwaibah suckled me as well as his father (Abu Salamah). So do not present to me your daughters and your sisters.

Narrated Aishah, Ummul Muminin: Aflah ibn AbulQu'ays entered upon me. I hid myself from him. He said: You are hiding yourself from me while I am your paternal uncle. She said: I said: From where? He said: The wife of my brother suckled you. She said: The woman suckled me and not the man. Thereafter the Messenger of Allah ﷺ entered upon me and I told him this matter. He said: He is your paternal uncle; he may enter upon you.

Aishah said the Messenger of Allah ﷺ visited her when a man was with her. The narrator Hafs said “this grieved him and he frowned”. The agreed version then goes, She said “He is my foster brother Messenger of Allah ﷺ”. He said “Consider, who are you brethren, for fosterage is consequent on hunger. ”

Abd Allaah bin Masud said “Fosterage is not valid except by what strengthens love and grows flesh. ” Abu Musa said “Do not ask us so long as this learned man is among us”

The aforesaid tradition has also been narrated by Ibn Masud through a different chain of narrators and to the same effect from the Prophet ﷺ. This version has the words anshaz al-‘azma meaning which nourishes bones and makes them sturdy and vigorous.

Aishah wife of the Prophet ﷺ and Umm Salamah said “Abu Hudaifah bin ‘Utbah bin Rabiah bin Abd Shams adopted Salim as his son and married him to his niece Hind, daughter of Al Walid bin ‘Utbah bin Rabiah. He (Salim) was the freed slave of a woman from the Ansar (the Helpers) as the Messenger of Allah ﷺ adopted Zaid as his son. In pre Islamic days when anyone adopted a man as his son, the people called him by his name and he was given a share from his inheritance. Allaah, the Exalted, revealed about this matter “Call them by (the name of) their fathers, that is juster in the sight of Allaah. And if ye know not their fathers, then (they are) your brethren in the faith and your clients. They were then called by their names of their fathers. A man, whose father was not known, remained under the protection of someone and considered brother in faith. Sahlah daughter of Suhail bin Amr Al Quraishi then came and said Messenger of Allah ﷺ, we used to consider Salim (our) son. He dwelled with me and Abu Hudhaifah in the same house, and he saw me in the short clothes, but Allaah the Exalted, has revealed about them what you know, then what is your opinion about him? The Prophet ﷺ said give him your breast feed. She gave him five breast feeds. He then became like her foster son. Hence, Aishah (may Allaah be pleased with her) used to ask the daughters of her sisters and the daughters of her brethren to give him breast feed five times, whom Aishah wanted to see and who wanted to visit her. Though he might be of age; he then visited her. But Umm Salamah and all other wives of the Prophet ﷺ refused to allow anyone to visit them on the basis of such breast feeding unless one was given breast feed during infancy. They told Aishah by Allaah we do not know whether that was a special concession granted by the Prophet ﷺ to Salim exclusive of the people.

Aishah said “In what was sent down in the Quran ten suckling’s made marriage unlawful, but they were abrogated by five known ones and when the Prophet ﷺ dies, these words were among what was recited in the Quran. ”

Aishah reported “The Messenger of Allah ﷺ as saying One or two sucks does not make marriage unlawful”.

Narrated Hajjaj ibn Malik al-Aslami: I asked: Messenger of Allah, what will remove from me the obligation due for fostering a child? He said: A slave or a slave-woman.