Al-Ahzab · 33:50

50. O Prophet! I have made permissible for you those of your wives whom you have given their dowry to, and those female servants that you possess from the captives Allah has given to you as booty. I have also made permissible for you, marriage to the daughters of your paternal uncles and aunts and the daughters of your maternal uncles and aunts, who have emigrated with you. I have also made permissible for you to marry the believing woman who presents herself to you for marriage without any dowry. The permissibility of this type of marriage, without a dowry, is exclusive to the prophet (peace be upon him), and is not permissible to anyone else from his Nation. Verily, I know what I have made obligatory upon the believers with regards to their wives: it is not permissible for them to marry more than four women at once. I am also aware of legislating for them with regards to their female servants: that they can make use of however many they want without any restriction on number. And I have also permitted for you from the aforementioned that which I have not made permissible for others, so that there is no difficulty or difficulty upon you. Allah Forgiving to those of His servants who repent, and is merciful to them.