Al-Lu'lu Wal-Marjan 920 — The Book of Ar-Rada' (Suckling foster relations)

Umm Habibah Narrated from:

I said, "O Allāh's Messenger! Do you like to have (my sister) the daughter of Abû Sufyân?" The Prophet صلى الله عليه وسلم said, "What shall I do (with her)?" I said, "Marry her." He said, "Do you like that?" I said, "(Yes), for even now I am not your only wife, so I like that my sister should share you with me." He said, "She is not lawful for me (to marry)." [1]I said, "We have heard that you want to marry." He said, "The daughter of Umm Salma!" I said, "Yes." He said, "Even if she were not my step-daughter, she would be unlawful for me to marry, for Thuwaiba suckled me and her father (Abû Salama)." [2] So you should neither present your daughters, nor your sisters to me."( Sahih Al-Bukhari, Hadith No. 42, Vol. 7 )