Sayyidah Umm Hani (may Allah be pleased with her) said: The Prophet (peace and blessings be upon him) proposed marriage to me, but I was not lawful for him (peace and blessings be upon him), because I had not emigrated. So this verse was revealed: "And the daughters of your paternal uncles, and the daughters of your paternal aunts, and the daughters of your maternal uncles, and the daughters of your maternal aunts who emigrated with you" [Al-Ahzab: 50].
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21373