"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)

"So the Quraish and the Ansar became angry and said, "He (i.e. the Prophet, ) gives the chief of Najd and does not give us." The Prophet said, "I give them) so as to attract their hearts (to Islam)." - Sahih Bukhari 4:55:558 (read more)

"beyond [known peoples of black West Africa] to the south there is no civilization in the proper sense. There are only humans who are closer to dumb animals than to rational beings. They live in thickets and caves, and eat herbs and unprepared grain. They frequently eat each other. They cannot be considered human beings." - Ibn Khaldun