Leviticus 25:47-49

And if one from another nation living among you gets wealth, and your countryman, at his side, becomes poor and gives himself for money to the man from another nation or to one of his family; After he has given himself he has the right to be made free, for a price, by one of his brothers, Or his father's brother, or the son of his father's brother, or any near relation; or if he gets money, he may make himself free.