Come, let us look one another in the face - This was a real declaration of war; and the ground of it is most evident from this circumstance: that the one hundred thousand men of Israel that had been dismissed, though they had the stipulated money, taking the advantage of Amaziah's absence, fell upon the cities of Judah, from Samaria to Beth-horon, and smote three thousand men, and took much spoil, 2 Chronicles 25:10-13. Amaziah no doubt remonstrated with Jehoash, but to no purpose; and therefore he declared war against him.
Amaziah‘s success against Edom had so elated him that he thought himself more than a match for his northern neighbor. The grounds of the quarrel between them were furnished by the conduct of the hired, but dismissed, Israelite soldiers (see the marginal reference).
Let us look one another in the face - i. e. “let us meet face to face in arms, and try each other‘s strength” 2 Kings 14:11-12.