II Chronicles 18:1-3

Jehoshaphat had riches and honor in abundance; and by marriage he allied himself with Ahab. After some years he went down to visit Ahab in Samaria; and Ahab killed sheep and oxen in abundance for him and the people who were with him, and persuaded him to go up with him to Ramoth Gilead. So Ahab king of Israel said to Jehoshaphat king of Judah, “Will you go with me against Ramoth Gilead?” And he answered him, “I am as you are, and my people as your people; we will be with you in the war.”