Quran never promotes slavery and never says slavery is right thing...
In fact: Islam has clearly and categorically forbidden the primitive practice of capturing a free man, to make him a slave or to sell him into slavery. On this point the clear and unequivocal words of [Muhammad(SAW)] are as follows:
"There are three categories of people against whom I shall myself be a plaintiff on the Day of Judgement. Of these three, one is he who enslaves a free man, then sells him and eats this money" (al-Bukhari and Ibn Majjah).
