Covenant of salt

[TonyChanYT]

Numbers 18:

19 All the holy contributions that the people of Israel present to the LORD I give to you, and to your sons and daughters with you, as a perpetual due. It is a covenant of salt forever before the LORD for you and for your offspring with you.”

Pulpit:

Salt was the natural emblem of that which is incorruptible; wherefore a binding alliance was (and still is) made by eating bread and salt together, and salt was always added to the sacrifices of the Lord (Leviticus 2:13; Mark 9:49). Numbers 18:19

Benson:

A covenant of salt — A durable and perpetual covenant; so called here, and 2 Chronicles 13:5, either because salt is of singular use to preserve things from corruption, and was an emblem of friendship; or because it was ratified on their part by salt, which is therefore called the salt of the covenant, for which the priests were obliged to take care that it should never be lacking from any meal-offering, Leviticus 2:13.

Similar imagery and significance was in 2 Chronicles 13:

5 Do you not know that the LORD, the God of Israel, has given the kingship of Israel to David and his descendants forever by a covenant of salt?