2 Chronicles 20:21 in the King James Version
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.
Context
20 They rose early in the morning and went out into the wilderness of Tekoa. As they went out, Jehoshaphat stood and said, “Listen to me, Judah and you inhabitants of Jerusalem! Believe in the LORD your God, so you will be established! Believe his prophets, so you will prosper.”
21 When he had taken counsel with the people, he appointed those who were to sing to the LORD and give praise in holy array as they go out before the army, and say, “Give thanks to the LORD, for his loving kindness endures forever.”
22 When they began to sing and to praise, the LORD set ambushers against the children of Ammon, Moab, and Mount Seir, who had come against Judah; and they were struck.