2 Chronicles (Author Compiled by Isaiah and Ezra from records of Nathan, Gad, Iddo, Ahijah, Jehu and others.)
20:23And the children of Ammon and Moab stood up against the inhabitants of mount Seir, to exterminate and destroy them; and when they had made an end of the inhabitants of Seir, they helped to destroy one another.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.