Ought you not to know,.... They did know what he afterwards says, but he would have them consider and acknowledge it:that the Lord God of Israel gave the kingdom over Israel to David for ever; to him and his seed, particularly to the Messiah, that should spring from him; but whether Abijah had this in view is a question, see 2Sa 7:13even to him and to his sons by a covenant of salt?
that is, a perpetual one, which was inviolable, and never to be made void; called so, because salt preserves from corruption and putrefaction, and because made use of in sacrifices offered when covenants were made; the Targum is,"as salt waters, which never lose their saltness.'