Leviticus 25:48-52

48after that he is sold there shall be right of redemption for him; one of his brethren may redeem him.

49Either his uncle or his uncle's son may redeem him, or one of his next relations of his family may redeem him; or if his means be sufficient, he may redeem himself.

50And he shall reckon with him that bought him from the year that he was sold to him unto the year of jubilee; and the price of his sale shall be according to the number of the years, according to the days of a hired servant shall he be with him.

51If there are yet many years, according unto them shall he return his redemption [money] out of the money that he was bought for;

52and if there remain but few years unto the year of jubilee, then he shall reckon with him; according unto his [remaining] years [of service] shall he give him back his redemption [money].