Leviticus 25:42-46

25:42 Since they are my servants whom I brought out from the land of Egypt, they must not be sold in a slave sale. 25:43 You must not rule over him harshly, but you must fear your God.

25:44 “‘As for your male and female slaves who may belong to you – you may buy male and female slaves from the nations all around you. 25:45 Also you may buy slaves from the children of the foreigners who reside with you, and from their families that are with you, whom they have fathered in your land, they may become your property. 25:46 You may give them as inheritance to your children after you to possess as property. You may enslave them perpetually. However, as for your brothers the Israelites, no man may rule over his brother harshly.