The Philosophy Of Islamic Slavery
Some of the reforms that grew out of the Zanj Rebellion were practical. Laws were passed to limit the concentration of slaves in any one area, for example, and breeding of slaves was strictly controlled with castration and by banning casual sex among them.
Other changes, however, were theological, as the institution of slavery came under religious guidance and rules that had been present since the time of Muhammad, such as the ban on keeping Muslim slaves. These reforms completed the conversion of slavery from a non-Islamic practice into a bona fide facet of Islam.
Slavery is mentioned nearly 30 times in the Quran, mostly in an ethical context, but some explicit rules for the practice are set out in the holy book.
Free Muslims must not be enslaved, for example, though captives and the children of slaves may become “those whom your right hand has possessed.” Foreigners and strangers were presumed to be free until shown to be otherwise, and Islam forbids racial discrimination in the matter of slavery, though in practice, black Africans and captured Indians have always made up the bulk of the slave populations in the Muslim world.
Slaves and their masters are definitively unequal – socially, slaves occupy a status similar to children, widows, and the infirm – but they are spiritual equals, technically under the stewardship of their masters, and will face Allah’s judgment in the same way when they die.
Contrary to some interpretations, slaves do not have to be freed when they adopt Islam, though masters are encouraged to educate their slaves in the religion. Freeing slaves was permissible in Islam, and many wealthy men either freed some of their own slaves or bought freedom for others’ as an act of atonement for sin. Islam requires the regular paying of alms, and this could be done by manumitting a slave.