Leviticus 27:21-24

When the Year of Celebration comes, the land becomes holy because it belongs to me, and it will be given to the priests. If you promise me a field that you have bought, its value will be decided by a priest, according to the number of years before the next Year of Celebration, and the money you pay will be mine. However, on the next Year of Celebration, the land will go back to the family of its original owner.