"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 ibn AbuDhubab: Iyas ibn Abdullah ibn AbuDhubab reported the Apostle of Allah (peace be upon him) as saying: Do not beat Allah's handmaidens, but when Umar came to the Apostle of Allah (peace be upon him) and said: Women have become emboldened towards their husbands, he (the Prophet) gave permission to beat them." - Sunan Abu Dawud 11:2141 (read more)

"Of the neighbors of the Bujja, Maqdisi had heard that "there is no marriage among them; the child does not know his father, and they eat people -- but God knows best. As for the Zanj, they are people of black color, flat noses, kinky hair, and little understanding or intelligence." - Al-Muqaddasi