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.