Leviticus 25:27, 51, 52

they are to determine the value for the years since they sold it and refund the balance to the one to whom they sold it; they can then go back to their own property.

If many years remain, they must pay for their redemption a larger share of the price paid for them.

If only a few years remain until the Year of Jubilee, they are to compute that and pay for their redemption accordingly.