2 Samuel 8:15

David was not so engaged in his wars abroad as to neglect the administration of the government at home. I. His care extended itself to all the parts of his dominion: He reigned over all Israel (Sa2 8:15); not only he had a right to reign over all the tribes, but he did so; they were all safe under his protection, and shared in the fruits of his good government. II. He did justice with an unbiased unshaken hand: He executed judgment unto all his people, neither did wrong nor denied or delayed right to any. This intimates, 1. His industry and close application to business, his easiness of access and readiness to admit all addresses and appeals made to him. All his people, even the meanest, and those too of the meanest tribes, were welcome to his council-board. 2. His impartiality and the equity of his proceedings, in administering justice. He never perverted justice through favour or affection, nor had respect of persons in judgment. Herein he was a type of Christ, who was faithful and true, and who doth in righteousness both judge and make war, Rev 19:11. See Psa 72:1, Psa 72:2. III. He kept good order and good officers in his court. David being the first king that had an established government (for Saul's reign was short and unsettled) he had the modelling of the administration. In Saul's time we read of no other great officer than Abner, that was captain of the host.

— Matthew Henry's Concise Commentary (public domain)

HIS REIGN. (Sa2 8:15-18) David executed judgment and justice unto all his people--Though involved in foreign wars, he maintained an excellent system of government at home, the most eminent men of the age composing his cabinet of ministers.

— Jamieson-Fausset-Brown Commentary (public domain)