2 Chronicles 20:21-22

21And 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."

22And 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.