Leviticus 25:53-55

He shall be with him as a yearly hired servant, and he shall not rule with rigor over him in your sight. And if he is not redeemed in these years, then he shall be released in the Year of Jubilee—he and his children with him. For the children of Israel are servants to Me; they are My servants whom I brought out of the land of Egypt: I am the LORD your God.