Quran: 4.24. Also (forbidden are) women already married, except those (captives and slaves) whom your right hands possess. Thus has Allah ordained for you. All others are lawful, provided you seek (them in marriage) with Mahr (bridal money given by the husband to his wife at the time of marriage) from your property, desiring chastity, not committing illegal sexual intercourse, so with those of whom you have enjoyed sexual relations, give them their Mahr as prescribed; but if after a Mahr is prescribed, you agree mutually (to give more), there is no sin on you. Surely, Allah is Ever All-Knowing, All-Wise.