"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)

"Narated By Abdullah ibn Abbas : The Prophet (pbuh) said: If you find anyone doing as Lot's people did, kill the one who does it, and the one to whom it is done." - Tirmidhi 1457 (read more)

"Unfortunately, this sin has become widespread in this day and age. In some narrations of Hadith there are severe warnings against this sin. It has been mentioned that the person who masturbates shall be resurrected on the Day of Judgment with a pregnant hand. It has also been mentioned that the ناکح الید (the one who masturbates) is under the curse of Allah." - Muhammad Akhtar Saheb