And whoever among you cannot [find] the means to marry free, believing women, then [he may marry] from those whom your right hands possess of believing slave girls. And Allāh is most knowing about your faith. You [believers] are of one another. So marry them with the permission of their people and give them their due compensation [i.e., mahr] according to what is acceptable. [They should be] chaste, neither [of] those who commit unlawful intercourse randomly nor those who take [secret] lovers. But once they are sheltered in marriage, if they should commit adultery, then for them is half the punishment for free [unmarried] women. This [allowance] is for him among you who fears affliction [i.e., sin], but to be patient is better for you. And Allāh is Forgiving and Merciful.

— Saheeh International