(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 likethat my sister should share the good with me." The Prophet (ﷺ) said, "But that is not lawful for me." Isaid, We have heard that you want to marry the daughter of Abu Salama." He said, "(You mean) thedaughter of Um Salama?" I said, "Yes." He said, "Even if she were not my step-daughter, she wouldbe 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 theProphet. When Abu Lahb died, one of his relatives saw him in a dream in a very bad state and askedhim, "What have you encountered?" Abu Lahb said, "I have not found any rest since I left you, exceptthat I have been given water to drink in this (the space between his thumb and other fingers) and thatis because of my manumitting Thuwaiba."