Leviticus 25:50-53

⁵⁰He shall reckon with him who bought him from the year that he sold himself to him to the Year of Jubilee. The price of his sale shall be according to the number of years; he shall be with him according to the time of a hired servant.

⁵¹If there are yet many years, according to them he shall give back the price of his redemption out of the money that he was bought for.

⁵²If there remain but a few years to the year of jubilee, then he shall reckon with him; according to his years of service he shall give back the price of his redemption.

⁵³As a servant hired year by year shall he be with him. He shall not rule with harshness over him in your sight.