A whole essay of apologetics for the Islamic position on slavery. Maybe someone with more patience and knowledge than me would like to take this apart:
Muhammad the Abolitionist: Slavery in the Qur'anThe existence of slavery is an ancient condition. It existed long before the Qur'an was revealed to Muhammad, starting in 610 C.E. What is interesting is comparing the depiction of slavery in the Qur'an to the Old and New Testament. In these older Jewish and Christian holy texts, a specific plan to eliminate the human bondage of our temporal present is never discussed. The Qur'an, on the other hand, not only recognized the immorality of slavery in seventh century Arabia, but sought to end it. The plan to do so is both implicit and explicit. To recognize this is to respect the Islamic attempt, in the name of Allah, to destroy an evil custom nearly thirteen centuries before America would legally and politically do the same...
The Prophet Muhammad did not believe that only the slaves of a particular race, religion, or ethnicity should be freed; instead, he desired to break the chains of slaves all over the world. The fact that the Qur'an did so with a specificity unparalleled in a monotheistic holy text makes it one of the greatest of anti-slavery books, and Muhammad himself one of the greatest of abolitionists. Peace be upon him.