The Book of Marriage (Kitab Al-Nikah)

Muslim :: Book 8 : Hadith 3430

'A'isha (Allah be pleased with her) reported: Allah's Messenger (may peace be upon him) visited me when a man was sitting near me, and he seemed to disapprove of that. And I saw signs of anger on his face and I said: Messenger of Allah, he is my brother by forsterage, whereupon he said: Consider who your brothers are because of fosterage since fosterage is through hunger (i. e. in infancy).