Leviticus 25:39-43

39“ ‘If any of your fellow Israelites become poor and sell themselves to you, do not make them work as slaves. 40They are to be treated as hired workers or temporary residents among you; they are to work for you until the Year of Jubilee. 41Then they and their children are to be released, and they will go back to their own clans and to the property of their ancestors. 42Because the Israelites are my servants, whom I brought out of Egypt, they must not be sold as slaves. 43Do not rule over them ruthlessly, but fear your God.