2 Chronicles 20:22

And when they began to sing and to praise, in a singular service of worship based upon faith in the victory promised to them, the Lord set ambushments against the children of Ammon, Moab, and Mount Seir which were come against Judah, and they were smitten. It seems that certain divisions of the invading hordes, eager for booty, had determined to waylay any forces that might come along. When these attacked their own confederates, however, the result was a wild self-slaughter of the invading army, every man regarding his neighbor as a traitor and an enemy.