And when he had taken counsel with the people, he appointed those who were to sing to the LORD and praise him in holy attire, as they went before the army, and say,
"Give thanks to the LORD, for his steadfast love endures forever."
And when they began to sing and praise, the LORD set an ambush against the men of Ammon, Moab, and Mount Seir, who had come against Judah, so that they were routed. – 2 Chrn 20:21-22 (ESV)
Jehoshaphat is faced with a large opposing army. He doesn’t make light of the force arrayed against him, but he does turn to the Lord. Then the Lord works while the people are praising Him (v 20:21-22). When they go to spy on the opposing force, they see only dead bodies, ready to loot. This is what God does; he turns the tables on our circumstances. The Lord works at this from both sides: God opposes the proud but gives grace to the humble.
