2 Chronicles 20:18-22 King James Version (KJV)
18 And Jehoshaphat bowed his head with his face to the ground: and all Judah and the inhabitants of Jerusalem fell before the Lord, worshipping the Lord.
19 And the Levites, of the children of the Kohathites, and of the children of the Korhites, stood up to praise the Lord God of Israel with a loud voice on high.
20 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 the Lord your God, so shall ye be established; believe his prophets, so shall ye prosper.
21 And when he had consulted with the people, he appointed singers unto the Lord, and that should praise the beauty of holiness, as they went out before the army, and to say, Praise the Lord; for his mercy endureth for ever.
22 And when they began to sing and to praise, the Lord set ambushments against the children of Ammon, Moab, and mount Seir, which were come against Judah; and they were smitten.