Leviticus 27:23 (KJV)

But the field, when it goeth out in the jubile, shall be holy unto the Lord, as a field devoted; the possession thereof shall be the priest’s.

And if a man sanctify unto the Lord a field which he hath bought, which is not of the fields of his possession;

Then the priest shall reckon unto him the worth of thy estimation, even unto the year of the jubile: and he shall give thine estimation in that day, as a holy thing unto the Lord.

In the year of the jubile the field shall return unto him of whom it was bought, even to him to whom the possession of the land did belong.

And all thy estimations shall be according to the shekel of the sanctuary: twenty gerahs shall be the shekel.