
The way the slave owners treated their slaves was inhumane, and God is Just, so I would say the salves prayers were answered. In other countries I believe there were ways to treat slaves that let them go free after 7 years, or they could pay for freedom, so we could ask this question in that instance. But since the slave owners didn’t see their slaves as people, (when all who are made in the image of God are equal) then God would not let the injustice last forever