The man of God whose word was ignored by kings Ahab and Jehoshaphat was
Elijah
Zedekiah
Malakiah
Micaiah
Correct answer is D
Ahab, the king of Israel, and Jehoshaphat, the king of Judah, were considering going to war against Ramoth-Gilead. Before proceeding, they sought the counsel of the prophets. Ahab's prophets were unanimously in favour of going to war but Jehoshaphat wanted to inquire if there was a prophet of the Lord available. Ahab then mentioned Micaiah, but he expressed a dislike for Micaiah because Micaiah's prophecies were often unfavourable to Ahab.
Micaiah delivered a prophecy that predicted Ahab's defeat and death in the upcoming battle. Despite this warning, Ahab chose to ignore Micaiah's words and went into battle where he was indeed mortally wounded.
Reference: 1 Kings 22.