Allah, the Blessed and Exalted, says: "Indeed, We have made lawful for you your wives" [Surah al-Ahzab: 50], up to His saying: "(This is) exclusively for you, not for the (other) believers." [Surah al-Ahzab: 50]
So Allah Almighty made lawful for him (peace and blessings be upon him), along with his (peace and blessings be upon him) wives, who were several in number, those women who were not his (peace and blessings be upon him) wives on the day this permission was revealed, (namely) the daughters of his (peace and blessings be upon him) paternal uncles, the daughters of his (peace and blessings be upon him) paternal aunts, the daughters of his (peace and blessings be upon him) maternal uncles and the daughters of his (peace and blessings be upon him) maternal aunts who emigrated with him (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / Q13351