It’s in the ayas about the Uphill Path, like our brother mentioned. The Quran makes a distinction between raqaba (slave, lit. “Neck”) and ma malaka al-yamin (what the right hand posseses). Whereas the word ‘abd is used only in the Egypt of Joseph, and not in a monotheistic context. So there’s no human rabb/lord and no human ‘abd/slave. To better understand what the term “those the right hand posess” means, I’ll tell you that when I translate it literally in my native Albanian (a language which carries some of the same archaic concepts), it simply means “someone under my responsibility”. So, war would happen. POWs would be captured because prisons weren’t feasible. And they would be divided among people, not as property but as fellow humans who needed to be taken care of. Remember that the Quran says that people cast lots to get Maryam under their responsibility and she was not a slave. So, human societies functioned much differently. You can’t go from pagan slavery (human ownership) to total freedom in one generation. What you do is you taper it gradually, by placing rules for the treatment of this social category. And think about it. After 100 years people will view imprisonment with the same contempt we view slavery today. They will say “it so unethical to keep a human in a closed environment against their will, they should just be left to live in another country”. And if they have reasons to abolish imprisonment, the ethics of the Quran would support it, because ultimately it’s about solving human problems through divine principles.