וַיַּבְדִּילֵ֣ם אֲמַצְיָ֗הוּ לְהַגְּדוּד֙ אֲשֶׁר־בָּ֤א אֵלָיו֙ מֵֽאֶפְרַ֔יִם לָלֶ֖כֶת לִמְקוֹמָ֑ם וַיִּ֨חַר אַפָּ֤ם מְאֹד֙ בִּֽיהוּדָ֔ה וַיָּשׁ֥וּבוּ לִמְקוֹמָ֖ם בָּחֳרִי־אָֽף׃ (פ)
Then Amaziah separated them, to wit, the army that was come to him out of Ephraim, to go back home; wherefore their anger was greatly kindled against Judah, and they returned home in fierce anger.
Read midrashic interpretation of II Chronicles 25:10: and classical rabbinic exegesis.