"Prohibited to you (For marriage) are:- Your mothers, daughters, sisters; father's sisters, Mother's sisters; brother's daughters, sister's daughters; foster-mothers (Who gave you suck), foster-sisters; your wives' mothers; your step-daughters under your guardianship, born of your wives to whom ye have gone in,- no prohibition if ye have not gone in;- (Those who have been) wives of your sons proceeding from your loins; and two sisters in wedlock at one and the same time, except for what is past; for Allah is Oft-forgiving, Most Merciful;" - Quran 4:23 (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)

"("Do you commit lewdness such as none preceding you has committed in all of the nations Verily, you practice your lusts on men instead of women.) meaning, you left women whom Allah created for you and instead had sex with men Indeed, this behavior is evil and ignorant because you have placed things in their improper places." - Ibn-Kathir