2 Chronicles 20:22 in the King James Version
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.
Context
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.
23 For the children of Ammon and Moab stood up against the inhabitants of Mount Seir to utterly kill and destroy them. When they had finished the inhabitants of Seir, everyone helped to destroy each other.