"Also (forbidden are) women already married, except those whom your right hands possess. Thus has Allah ordained for you. All others are lawful, provided you seek them from your property, desiring chastity, not fornication. So with those among them whom you have enjoyed, give them their required due, but if you agree mutually after the requirement (has been determined), there is no sin on you. Surely, Allah is Ever All-Knowing, All-Wise." - Quran 4:24 (read more)

"Narrated 'Abdullah bin 'Umar : The Jew brought to the Prophet a man and a woman from amongst them who have committed (adultery) illegal sexual intercourse. He ordered both of them to be stoned (to death), near the place of offering the funeral prayers beside the mosque." - Sahih Bukhari 7:62:64 (read more)

"If the wife goes against his wishes and refuses to obey him, the husband has to take a gradual approach in handling the matter. First he should admonish her and remind her of the punishment for disobeying his command. If that does not succeed, then he moves on to forsaking her in bed. If that does not work, then he may hit her, but in a manner that is not severe, and there is nothing wrong with also threatening her with divorce." - Islam Q&A