Not lawful to you are women after , nor for you to exchange them for wives, even if their beauty were to please you, except what your right hand possesses. And ever is Allah , over all things, an Observer. (Quran 33:52)
Why Allah here supports slavery of women.
Peace be on all.
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The truth abut female slaves is that foes of Muslims in Holy Prophet (s.a.w.)'s time persecuted Muslims in various heinous ways; murder, cutting hand feet and nose etc of martyrs, killing children, dragging on hot sand with stones on chest, abduction of ladies to use as slaves etc.
For a long times, those Muslims were commanded to show patient.
When matter crossed limits, God allowed equal retaliation so that cruel people stop. Surely God is Kind but He is Just too......... This was His sense of Honour which sank people of Noah and turned the earth on people of Lot. Same treatment was eventually done with barbarics in the time of early Islam when they would not stop hurting believing women.
Now such conditions are absent, so as such slave making.
(Gist: Discourse by Ahmadiyya Muslim Promised Messiah Mahdi (on whom be peace), Ruhani Khazain, Vol 23, alislam.org]
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Elucidation of Freedom, Slavery and Islamic teachings (By Ahmadiyya Muslim Khalifah a.t.)
https://www.alislam.org/friday-sermon/2011-11-25.html
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[90:11] And We have pointed out to him (man) the two highways (of good and evil).
[90:12] But he attempted not the ascent (courageously).
[90:13] And what should make thee know what the ascent is?
[90:14] (It is) the freeing of a slave.
[90:15] Or feeding in a day of hunger.
[90:16] An orphan near of kin,
[90:17] Or a poor man (lying) in the dust.
[90:18] Again, he should have been of those who believe and exhort one another to perseverance and exhort one another to mercy.
[90:19] These are the people of the right hand.
[90:20] But those who disbelieve Our Signs, they are the people of the left hand.
(alislam.org/quran)
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Holy Quran is for all times with no abrogation; all necessary and possible commandments for human society are present in it.
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It is not fun subject; latter people used it as licence. It is a subject of crying and sorrow.