Bible Verses About Salt: Ratifying covenants

All the firstfruits of the sanctuary which the children of Israel offer to the Lord, I have given to thee and to thy sons and daughters, by a perpetual ordinance. It is a covenant of salt for ever before the Lord, to thee and to thy sons.

Do you not know that the Lord God of Israel gave to David the kingdom over Israel for ever, to him and to his sons by a covenant of salt?