"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)

"Our people [the Muslims] observing thus the occupations of the Jews and the Christians concluded that the religion of the Jews must compare unfavorably as do their professions, and that their unbelief must be the foulest of all, since they are the filthiest of all nations. Why the Christians, ugly as they are, are physically less repulsive than the Jews." - al-Jahiz