2 Chronicles 13:5 - Joseph Benson’s Commentary on the Old and New Testaments

By a covenant of salt A perpetual covenant. The reason of this mode of expression seems to arise from the preserving nature of salt; which, therefore, was made a symbol of friendship and fidelity. It is most likely, that in all solemn covenants which were confirmed by sacrifice, it was an ancient custom to offer salt with the sacrifice, to denote the faith and perpetuity of the covenant; so that, in this view, a covenant of salt will signify a covenant confirmed by sacrifice. See note on Numbers 18:19.