Sahih Bukhari

Narrated Um Habiba:(daughter of Abu Sufyan) I said, ""O Allah's Messenger (ﷺ)! Marry my sister. the daughter of Abu Sufyan."" The Prophet (ﷺ) said, ""Do you like that?"" I replied, ""Yes, for even now I am not your only wife and I like that my sister should share the good with me."" The Prophet (ﷺ) said, ""But that is not lawful for me."" I said, We have heard that you want to marry the daughter of Abu Salama."" He said, ""(You mean) the daughter of Um Salama?"" I said, ""Yes."" He said, ""Even if she were not my step-daughter, she would be unlawful for me to marry as she is my foster niece. I and Abu Salama were suckled by Thuwaiba. So you should not present to me your daughters or your sisters (in marriage)."" Narrated 'Urwa: Thuwaiba was the freed slave girl of Abu Lahb whom he had manumitted, and then she suckled the Prophet. When Abu Lahb died, one of his relatives saw him in a dream in a very bad state and asked him, ""What have you encountered?"" Abu Lahb said, ""I have not found any rest since I left you, except that I have been given water to drink in this (the space between his thumb and other fingers) and that is because of my manumitting Thuwaiba