My paternal uncle through fosterage came and asked permission to enter, but I refused to allow him till I asked God’s Messenger. When he came I asked him and he said, “He is your paternal uncle, so give him permission.” I replied, “Messenger of God, it was only the woman who suckled me and not the man” whereupon he said, “He is your paternal uncle, so let him come in where you are.” That was after seclusion was instituted for us.
‘Ali said, “Messenger of God, would you like the daughter of your paternal uncle Hamza, for she is the most beautiful girl in Quraish?” He replied, “Do you not know that Hamza is my foster-brother, and that God has prohibited by reason of fosterage what He has prohibited by reason of genealogy?”