The fact that in Mohammedan law every woman must belong to some man as his absolute property, either as a child, a wife, or a concubine, must delay the final extinction of slavery until the faith of Islam has ceased to be a great power among men.
The Hidayah lays down that “if the Mussulmans subdue an infidel territory before any capitation tax be established, the inhabitants, together with their wives and children, are all plunder, and the property of the state, as it is lawful to reduce to slavery all infidels, whether they be Kitabees, Majoosees or idotters.” The Hidayah also lays down that “whoever slays an infidel is entitled to his private property,” which invariably included his women and children.
The object, in the purchase of a female slave, is cohabitation and generation of children.
Muslims are allowed to cohabit with any of their female slaves. Surah iv. 3: "Then marry what seems good to you of women, by twos, or threes, or fours; and if ye fear that ye cannot be equitable, then only one, or what your right hands possess." Surah iv, 29: "Take of what your right hands possess of young women." Surah xxxiii. 49 "O prophet! verily We make lawful for thee wives to whom thou hast given their hire (dowry), and what thy right hand possesses out of the booty God hath granted thee."
Muslims are excused from strict rules of decorum in the presence of their female slaves, even as in the presence of their wives. Surah xxiii. 5: "Those who are strict in the rules of decorum, except for their wives, or what their right hands possess." See also Surah lxx. 29.
The helpless position of the slave is regards his master illustrates the helpless position of the false gods of Arabia in the presence of their Creator. Surah xvi. 77: "God has struck out a parable, an owned slave, able to do nothing, and one provided with a good provision, and one who expends therefrom in alms secretly and openly, shall they be held equal? Praise be to God, most of them do not know!" See also Surah xxx. 27.
Muslims shall exercise kindness towards their slaves. Surah iv. 44) "Serve God and do not associate aught with Him, and show kindness to your parents and to kindred and to that which your right hands possess."
When slaves can redeem themselves it is the duty of Muslims to grant the emancipation Surah xxiv. 33: "And such of those whom your right hands posses as crave a writing (i.e. a document of freedom), write it, out for them if ye know any good in them, and give them of the wealth of God which He has given you. And do not compel your slave-girls to prostitution if they desire to keep continent."
And concerning slavery, that was when slavery was a world-wide structure and which was conducted amongst Muslims and their enemies in the form of enslaving of prisoners of war. And it was necessary for Islam to adopt a similar line of practise until the world devised a new code of practise during war other than enslavement.