1 Kings 22:29

Went up. It might have been expected that Jehoshaphat, who had asked for a prophet of the Lord (v. 5), would heed the prophet’s message and refuse to go upon the expedition Micaiah had foretold would end in disaster. He had, it is true, rashly committed himself, by a solemn promise (v. 4), to take part in the war, and he was evidently bound to Ahab by a military alliance, yet he could have made it clear to Ahab that he could not go contrary to the will of the Lord. Indeed, by so doing he might have dissuaded Ahab from undertaking the war. By his willingness to accompany Ahab, Jehoshaphat was encouraging Ahab to court disaster. As it was, Jehoshaphat received a severe rebuke from the Lord for having joined in this enterprise (2 Chron. 19:2).