Charles Ellicott Commentary 2 Kings 14:8

"Then Amaziah sent messengers to Jehoash, the son of Jehoahaz son of Jehu, king of Israel, saying, Come, let us look one another in the face." — 2 Kings 14:8 (ASV)

Then. —After the subjugation of Edom. The more extended narrative which follows is clearly taken from a different source than the brief extract preceding it.

Come, let us look one another in the face. —A challenge to battle, the basis of which might be found in the outrages committed by the Israelite mercenaries on their homeward march. It appears likely, however, that Amaziah, intoxicated by his recent success, aimed at nothing less than the recovery of the Ten Tribes for the house of David. So Josephus (Antiquities ix. 9, § 2), who gives what purport to be the letters which passed between the two kings on this occasion.