2 Chronicles 20:20-23

And they rose early in the morning, and went forth into the wilderness of Tekoa: and as they went forth, Jehoshaphat stood and said, Hear me, O Judah, and ye inhabitants of Jerusalem: believe in Jehovah your God, so shall ye be established; believe his prophets, so shall ye prosper. And when he had taken counsel with the people, he appointed them that should sing unto Jehovah, and give praise in holy array, as they went out before the army, and say, Give thanks unto Jehovah; for his lovingkindness endureth for ever. And when they began to sing and to praise, Jehovah set liers-in-wait against the children of Ammon, Moab, and mount Seir, that were come against Judah; and they were smitten. For the children of Ammon and Moab stood up against the inhabitants of mount Seir, utterly to slay and destroy them: and when they had made an end of the inhabitants of Seir, every one helped to destroy another.