Leviticus 27:16-24

And if a man shall sanctify unto the LORD some part of a field of his possession, then thy estimation shall be according to the seed thereof: an homer of barley seed shall be valued at fifty shekels of silver.

If a man ... In the case of acquired property in land, if not redeemed, it returned to the donor at the Jubilee; whereas the part of a hereditary estate which had been vowed did not revert to the owner, but remained attached in perpetuity to the sanctuary. The reason of this remarkable difference was to lay every man under an obligation to redeem the property, or stimulate his nearest kinsman to do it, in order to prevent a patrimonial inheritance going out from any family in Israel.