Leviticus 25:46-49

And ye shall take them as an inheritance for your children after you, to inherit {them for} a possession; they shall be your bondmen for ever: but over your brethren the children of Israel, ye shall not rule one over another with rigour. {they...: Heb. ye shall serve yourselves with them} And if a sojourner or stranger wax rich by thee, and thy brother {that dwelleth} by him wax poor, and sell himself unto the stranger {or} sojourner by thee, or to the stock of the stranger's family: {wax rich...: Heb. his hand obtain, etc} After that he is sold he may be redeemed again; one of his brethren may redeem him: Either his uncle, or his uncle's son, may redeem him, or {any} that is nigh of kin unto him of his family may redeem him; or if he be able, he may redeem himself.