Bible Notes Online - 2-Samuel 8 - ESV
Commentary

v1-14: David defeated numerous heathen armies; Philistines, Moabites, Syrians (Arameans); Edom, Ammon, Amalek, Zobah. These nations became subject to David, and brought tribute to him. This produced the largest area over which Israel ruled, and Solomon inherited this vast area, fulfilling Gen 15.18.

See also Rev 11.15; 21.24, where the kingdoms of this world become the kingdoms of Christ, and the nations bring their tribute to Him. In this way, David pictures Christ as the mighty King.

The Lord God gave David victory, and David acknowledged that fact, dedicating articles to Him.

v15-18: David instituted just leadership, delegating authority to others. See 23.3