Leviticus 25:27, 51-52

then let him reckon the years of the sale thereof, and restore the overplus unto the man to whom he sold it; and he shall return unto his possession.

If there be yet many years, according unto them he shall give back the price of his redemption out of the money that he was bought for. And if there remain but few years unto the year of jubilee, then he shall reckon with him; according unto his years shall he give back the price of his redemption.