וַיַּ֧עַל מֶֽלֶךְ־יִשְׂרָאֵ֛ל וִֽיהוֹשָׁפָ֥ט מֶֽלֶךְ־יְהוּדָ֖ה אֶל־רָמֹ֥ת גִּלְעָֽד׃
So the king of Israel and Jehoshaphat the kind of Judah went up to Ramoth-gilead.
Read midrashic interpretation of II Chronicles 18:28: and classical rabbinic exegesis.