Albert Barnes Commentary 1 Chronicles 13:1

"And David consulted with the captains of thousands and of hundreds, even with every leader." — 1 Chronicles 13:1 (ASV)

The captains ... - Such an organization had probably been established generally throughout the tribes before the time of David, but David seems to have been the first to recognize these officers of the army as representatives of the people, to consult them on public affairs, and to give them a certain political position.