What did the Prophet Muhammad (saw) say in response to Um Habiba's suggestion to marry her sister?
 Narrated Um Habiba:                     I said, "O Allah's Apostle! Do you like to have (my sister) the daughter of Abu Sufyan?" The Prophet 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)." I said, "We have heard that you want to marry." He said, "The daughter of Um Salama?" I said, "Yes." He said, "Even if she were not my stepdaughter, she should be unlawful for me to marry, for Thuwaiba suckled me and her father (Abu Salama). So you should neither present your daughters, nor your sisters, to me."