سورة An-Noor ( The Light ) - الآية 33

And those, who cannot find a match, should observe continence till Allah provides them with means out of His bounty And if those who are in your possession, ask for a deed of emancipation, execute the deed of emancipation with them, provided that you find some good in them; and give them something out of the means Allah has given you. And do not force your slave-girls into prostitution for your own worldly gains when they themselves want to keep chaste; and if anyone forces them into it, after such a compulsion Allah will be forgiving and merciful for them.