An-Nisaa 4:25

But if any of you cannot afford to marry free believing women, you may marry believing bondwomen in your possession. Allah knows best about your faith; you are from one another. Marry them with the permission of their masters and give them their dowries in fairness – provided that they are chaste, neither given to committing fornication nor having secret paramours. If they commit adultery after marriage, they are liable to half of the punishment prescribed for free women[18]. This is for those of you who fear falling into sin; but if you stay patient, it is better for you. And Allah is All-Forgiving, Most Merciful.

[18] Their punishment is fifty (50) lashes; neither stoning to death nor exile.

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.

25. And whoever of you have not the means wherewith to wed free, believing women, they may wed believing girls from among those (slaves) whom your right hands possess, and Allâh has full knowledge about your Faith; you are one from another. Wed them with the permission of their own folk (guardians, Auliyâ’ or masters) and give them their Mahr according to what is reasonable; they (the above said captive and slave-girls) should be chaste, not committing illegal sex, nor taking boy-friends. And after they have been taken in wedlock, if they commit illegal sexual intercourse, their punishment is half that for free (unmarried) women.[7] This is for him among you who is afraid of being harmed in his religion or in his body; but it is better for you that you practise self-restraint, and Allâh is Oft-Forgiving, Most Merciful.

[7] (V.4:25) Female or male slaves (married or unmarried); if they commit illegal sexual intercourse, their punishment is fifty (50) lashes (half of that which is for free unmarried women); neither stoning to death nor exile.

And whoso is not able to afford to marry free, believing women, let them marry from the believing maids whom your right hands possess. Allah knoweth best (concerning) your faith. Ye (proceed) one from another; so wed them by permission of their folk, and give unto them their portions in kindness, they being honest, not debauched nor of loose conduct. And if when they are honourably married they commit lewdness they shall incur the half of the punishment (prescribed) for free women (in that case). This is for him among you who feareth to commit sin. But to have patience would be better for you. Allah is Forgiving, Merciful.