And Jehoiada made a covenant between the LORD and the king and the people, that they should be the LORD's people; between the king also and the people.
Deuteronomy 29:10-13
Ye stand this day all of you before the LORD your God; your captains of your tribes, your elders, and your officers, with all the men of Israel, Your little ones, your wives, and thy stranger that is in thy camp, from the hewer of thy wood unto the drawer of thy water: That thou shouldest enter into covenant with the LORD thy God, and into his oath, which the LORD thy God maketh with thee this day: That he may establish thee to day for a people unto himself, and that he may be unto thee a God, as he hath said unto thee, and as he hath sworn unto thy fathers, to Abraham, to Isaac, and to Jacob.
Jehoiada's threefold covenant — between the LORD, the king, and the people — replicates the constitutional structure of the Deuteronomy 29 covenant ceremony. The Deuteronomic covenant ceremony formally constituted Israel as the LORD's people and bound the king and community to covenant obligation. Jehoiada's restoration of the covenant in the wake of Athaliah's usurpation constitutes a statutory covenant renewal, re-establishing the tripartite relationship that the Deuteronomic ceremony prescribed and that Athaliah's reign had severed.