2 Chronicles 17:9

And they taught in Judah, &c. The Levites and priests were teachers by office, Deuteronomy 33:10. It was a part of the work for which they had their maintenance, and indeed had little else to do. But, it seems, they had neglected it, pretending, probably, that they could not get the people to hear them. Jehoshaphat, therefore, sends them with the princes, who, by their authority, might require the people to assemble together to receive instruction in the laws of God and their duty. “What a great deal of good,” says Henry, “may be done, when Moses and Aaron thus go hand in hand in the doing of it; when princes with their power, and priests and Levites with their Scripture-learning, agree to teach the people the good knowledge of God, and their duty. These itinerant judges, and itinerant preachers together, were instrumental to diffuse a blessed light throughout the cities of Judah.” And had the book of the law of the Lord with them 1st, For their own guidance, that from thence they might draw all the instructions they gave to the people, and not teach for doctrines the commandments of men. 2d, For the conviction or the people, that they might see these priests and Levites had a divine warrant for what they said, and delivered to them only that which they had received from the Lord.