It is narrated from Sayyiduna Ali (may Allah be pleased with him), he says: I said, "O Messenger of Allah! You prefer kinship among the Quraysh and leave us, that is, Banu Hashim." The Prophet (peace and blessings be upon him) said: "Do you have any kinship?" I said: "Yes, there is the daughter of Sayyiduna Hamza (Salma)." The Prophet (peace and blessings be upon him) said: "She is not lawful for me, because she is my foster niece."

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that when the Messenger of Allah (peace and blessings be upon him) was informed about marrying the daughter of Sayyiduna Hamza, he (peace and blessings be upon him) said: She is my foster niece, and the relationship made unlawful by suckling is the same as that made unlawful by lineage, so she is not lawful for me.

Narrated by Sayyida Aisha (may Allah be pleased with her) that the Noble Prophet (peace and blessings be upon him) said: The relationship that becomes unlawful due to suckling (breastfeeding) is the same as that which becomes unlawful due to lineage, such as maternal uncle, paternal uncle, nephew, etc.

It is narrated from Sayyida Aisha (may Allah be pleased with her) that Aflaḥ, the brother of Abu Qu‘ais, sought permission to come to me, but I refused. When the Noble Prophet (peace and blessings be upon him) arrived, I said: O Messenger of Allah! Aflaḥ, the brother of Abu Qu‘ais, sought permission to come to me, but I did not allow him. The Prophet (peace and blessings be upon him) said: Allow him to come. I said: The woman nursed me, not the man? The Prophet (peace and blessings be upon him) said: May your right hand be covered in dust! Allow him to come, he is your foster-uncle.