No ruler or progenitor was allowed to treat his subjects or...

No ruler or progenitor was allowed to treat his subjects or offspring as his slaves. Every individual was bestowed with well-defined rights; the ruler and the ruled, the progenitor and the offspring had to live within the limits prescribed by religion; no one could transgress those limits. And it drastically restricted the first cause, i.e., war, by allowing enslavement only in a war fought against unbelieving enemy. In no other way could anyone be enslaved.

At the same time, Islam raised the status of slavery to that of a free man; and opened many ways for their emancipation.[^3] Before slave trade was started on a large scale by the Westerners (when colonisation began), it was only in wars that men were made captives. But Islam did not permit wars of aggression. All the battles fought during the life-time of the Prophet were defensive battles.

Not only this, an alternative was also introduced and enforced: “…..to let the captives go free, either with or without any ransom “(The Qur'an 47:4). In the battles forced upon the Muslims, the Prophet had ordered very humane treatment of the prisoners who fell into Muslim hands. They could purchase their freedom on payment of small sums of money, and some of them were left off without any payment.

It all depended upon the discretion of the Prophet or his rightful successors, keeping in view the safety of the Muslims and the extent of danger from the enemy.

The captives of the very first Islamic battle, Badr, were freed on ransom (in form of money or work like teaching ten Muslim children how to read and write), while those of the tribe of Tay were freed without any ransom.[^4] Even in such enslavement a condition was attached that a mother was not to be separated from her child, nor brother from brother nor husband from wife nor one member of a clan from his clan.

The Prophet and the first Shi'ite Imam, 'Ali bin Abi Talib, prescribed severest penalties for anyone who took a free man into slavery: cutting off the hand of the culprit. Ameer Ali writes in Mohammedan Law: The possession of a slave by the Koranic laws was conditional on a bona-fide war, waged in self-defence, against idolatrous enemies; and it was permitted in order to serve as a guarantee for the preservation of the lives of the captives..