An-Nur · 24:33

33. Those who are unable to marry due to their poverty should seek chastity from fornication until Allah makes them wealthy through His vast grace. Those servants who wish to make a contract with their masters, to give money so that they can be free, their masters should accept that of them if they know they have the ability to fulfil and are upright in religion. It is necessary upon them to give them from the wealth Allah has granted them, by discounting them a portion of what they agreed to pay. And do not force your slave girls to fornicate, in pursuit of wealth, as Abdullah ibn Ubayy did with his two slave girls when they requested chastity and staying far from fornication, to seek what she earns through her private parts. Whoever forces them to do that, Allah is Forgiving of their sins after their being forced and Merciful to them, because they are being forced, and the sin is upon the one who forces them.