Albert Barnes Commentary 2 Chronicles 23:16

"And Jehoiada made a covenant between himself, and all the people, and the king, that they should be Jehovah`s people." — 2 Chronicles 23:16 (ASV)

Between him... In 2 Kings 11:17, the covenant is said to have been made between the Lord. To the writer of Chronicles, Jehoiada was God’s representative and therefore received the pledges of the king and people.