Even if she was not my stepdaughter whom I raised, she would still be unlawful for me because she is my niece through suckling. Thuwaybah breastfed me and Abu Salāmah (her father). So, do not offer me your daughters or sisters

Umm Habībah, the daughter of Abu Sufyān, is one of the Mothers of the Believers (may Allah be pleased with them all), and she was ecstatic about her marriage to the Messenger of Allah (may Allah's peace and blessings be upon him). So she asked the Prophet (may Allah's peace and blessings be upon him) to marry her sister.

The Prophet (may Allah's peace and blessings be upon him) expressed wonder at her request, due to women’s extreme jealousy regarding the matter, as she would allow herself to have a co-wife. Hence, he asked her in astonishment: Would you like that? And she replied in the affirmative. Then, she explained to him the reason why she wanted him to marry her sister.

It was inevitable that she would have to share him with other women and that she would not be his only wife, so she wanted her sister to be the one who would share this great goodness with her . It was as if she was not aware of the prohibition of being married to two sisters at the same time. That is why the Prophet (may Allah's peace and blessings be upon him) informed her that her sister was not lawful for him.

Then, she told him that she heard that he would marry the daughter of Abu Salamah. So to be sure, he asked her: Do you mean the daughter of Umm Salamah? She said: Yes. Then, in order to clarify the falsehood of this rumor, he told her that the daughter of Umm Salamah was not lawful for him for two reasons: First: she is his stepdaughter whom he has brought up, because she is his wife’s daughter.

Second: she is his niece through suckling, because Thuwaybah, the ex-slave girl of Abu Lahab, had breastfed him and her father Abu Salamah. So, he is her paternal uncle as well. So, he instructed them not offer him their daughters or sisters in marriage, for he knows better how to manage his affairs in this regard.