Komentarz do Diwrej ha-jamim I 11:3

and David made with them a covenant Like the covenant that Jehoiada made, as it is written (II Kings 11:17): “And Jehoiada enacted the covenant between the Lord and between the king and between the people, to be the people of the Lord.” The meaning is [that they agreed] to be servants of the Lord, and also “between the king and between the people,” to be his servants according to the king’s judgment, and also that the king should do according to the law for his servants; to wage their wars.

before the Lord But is it not so that the Tabernacle was not in Hebron? What then is the meaning of “before the Lord”? Wherever people make a stipulation or enact a covenant, the Omnipresent is there. A similar instance [is found] in [the case of] Jephthah: (Jud. 11:11): “before the Lord in Mizpah.” [Another] similar instance (Lev. 5:21): “and commits an act of treachery against the Lord by making a denial to his neighbor,” as is explained in Torath Kohanim (ad loc.).