Albert Barnes Commentary 2 Chronicles 25:13

"But the men of the army whom Amaziah sent back, that they should not go with him to battle, fell upon the cities of Judah, from Samaria even unto Beth-horon, and smote of them three thousand, and took much spoil." — 2 Chronicles 25:13 (ASV)

To avenge the insult (2 Chronicles 25:10), the troops of Joash proceeded southward and ravaged all the Jewish towns and villages between the Israelite frontier and Beth-horon. This invasion probably took place while Amaziah was still in Edom.