Numbers 18:19

All the holy offerings that the Israelites present to the Lord I give to you and to your sons and daughters as a permanent statute. It is a permanent covenant of salt before the Lord for you and your offspring.”

Note That is, a perpetual covenant

All the heave offerings of the holy things, which the children of Israel offer unto the Lord, have I given thee, and thy sons and thy daughters with thee, by a statute for ever: it is a covenant of salt for ever before the Lord unto thee and to thy seed with thee.

All the wave offerings of the holy things which the children of Israel offer to the Lord, I have given you and your sons and your daughters with you, as a portion forever. It is a covenant of salt forever before the Lord to you and to your offspring with you.”

All the heave-offerings of the holy things, which the children of Israel offer unto Jehovah, have I given thee, and thy sons and thy daughters with thee, as a portion for ever: it is a covenant of salt for ever before Jehovah unto thee and to thy seed with thee.