Charles Ellicott Commentary 2 Chronicles 20:23

"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." — 2 Chronicles 20:23 (ASV)

Stood up against. — ‘Amad ‘al, a late usage. (So 1 Chronicles 21:1.)

Utterly to slay. — To exterminate (ha c harîm), devote to destruction.

Made an end of. — Finished with. (See on 2 Chronicles 20:22, “begin with,” and compare Genesis 44:12.)

Every one helped ... another. — Literally, they helped, each against (or, in the case of) his fellow, for destruction (mash c hîth, 2 Chronicles 22:4; Ezekiel 5:16).