2 Chronicles 20:22-23

22And when they began to sing and to praise, the LORD set ambushes against the children of Ammon, Moab, and mount Seir, who were come against Judah; and they were smitten.123 23For 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.4