Leviticus 25:52-56

And if there remain but few years unto the year of jubile, then he shall count with him, and according unto his years shall he give him again the price of his redemption.

And as a yearly hired servant shall he be with him: and the other shall not rule with rigour over him in thy sight.

And if he be not redeemed in these years, then he shall go out in the year of jubile, both he, and his children with him.

For unto me the children of Israel are servants; they are my servants whom I brought forth out of the land of Egypt: I am the LORD your God.