Leviticus 25:42-46

The people of Israel are my servants, whom I brought out of the land of Egypt, so they must never be sold as slaves. Show your fear of God by not treating them harshly. “However, you may purchase male and female slaves from among the nations around you. You may also purchase the children of temporary residents who live among you, including those who have been born in your land. You may treat them as your property, passing them on to your children as a permanent inheritance. You may treat them as slaves, but you must never treat your fellow Israelites this way.