Bible Verses About Salt: Ratifying covenants

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.

Ought ye not to know that Jehovah, the God of Israel, gave the kingdom over Israel to David for ever, even to him and to his sons by a covenant of salt?