II Chronicles - Chapter 18
400 to 1
Yehoshafat forged a treaty with the kingdom of the Ten Tribes by marrying the sister of Ahab, who was then their king. Eventually, Yehoshafat went to visit Ahab, who persuaded Yehoshafat to join him in a military campaign. Yehoshafat wanted to consult with a prophet before going to war so Ahab (who was an idolatrous king) summoned 400 of his "prophets." Predictably, they all said what they knew their king wanted to hear. Yehoshafat asked to hear from an actual prophet of G-d. Since Ahab's wife, Jezebel, had killed all of G-d's prophets, there was only one available: Michayahu, whom Ahab hated because his prophecies were always negative. (Well, negative for Ahab, at least.)
Michayahu was summoned and, sure enough, he didn't tell Ahab what he wanted to hear. When Michayahu arrived, a false prophet named Tzidkiyahu was displaying iron horns as a sign how Ahab would gore his enemies. Michayahu contradicted him and told Ahab that he would die in battle and his troops would scatter. When Ahab complained that Michayahu had foretold evil for him once again, the prophet explained why the 400 false prophets all foretold a different story: G-d had sent the spirit of Naboth (who had been killed so that Ahab could have his vineyard) to put lies in their mouths in order to lure Ahab to his doom.
Tzidkiyahu didn't like hearing this, so he struck Michayahu and called him a liar. Michayahu prophesied that when his words came true, Tzidkiyahu will be forced to hide. Ahab ordered Michayahu thrown in jail until he returned, but the prophet rejoined that the king would not be coming back.
Ahab and Yehoshafat went to war against Aram. Ahab took off his royal robes and disguised himself as an ordinary soldier in an attempt to thwart the prophecy against him. At first, the enemy thought that Yehoshafat was Ahab and they directed their attack towards him, but they soon realized their misidentification and redirected their attack. Ahab was struck by a random arrow and was removed from the battle. The battle waged on but Ahab expired at sunset.