Musnad Imam Shafi'i

Umm Habibah bint Abu Sufyan (may Allah be pleased with her) narrates: She said, "O Messenger of Allah ﷺ! Are you interested in my sister, the daughter of Abu Sufyan?" The Messenger of Allah ﷺ replied, "What would I do?" Umm Habibah (may Allah be pleased with her) said, "You should marry her." He ﷺ said, "Your sister?" She said, "Yes." He ﷺ said, "Would you like that?" (that your sister would be your co-wife) She said, "Yes, I am not alone with you, and I would like to share goodness and blessing with my sister." He ﷺ said, "That is not lawful for me." Umm Habibah (may Allah be pleased with her) says, I said, "By Allah! I have been informed that you are going to marry the daughter of Abu Salamah." He ﷺ said, "The daughter of Abu Salamah?" She said, "Yes." He ﷺ said, "By Allah! Even if she were not my stepdaughter and under my guardianship, she would still not be lawful for me, because she is the daughter of my foster brother. Both her father and I were suckled by Thuwaybah. Therefore, do not offer your daughters and sisters to me for marriage."