2 Chronicles 20:23 in the World English Bible
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.
Context
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.
23 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.
24 And when Judah came toward the watch tower in the wilderness, they looked unto the multitude, and, behold, they were dead bodies fallen to the earth, and none escaped.