Abdullah bin Yusuf al-Tunaysi عبد الله بن يوسف التنيسي · The Book of Marriage

"We have been saying that you want to marry Durrah bint Abi Salamah." The Messenger of Allah said: "As a co-wife to Umm Salamah? Even if I were not married to Umm Salamah, she would not be permissible to me, for her father is my brother through breast-feeding."