2 Chronicles 18:4

And Jehoshaphat said unto the king of Israel, Enquire, I pray thee, at the word of the LORD to day.

Jehoshaphat asked Ahab to inquire at the word of the Lord that day before going forward. The inquiry concerned their proposed joint campaign for war at Ramoth-gilead. Although he had rashly promised to join Ahab, he still sought to learn God's will before proceeding.

The favorable answer returned by Ahab's false prophets left Jehoshaphat unsatisfied. He insisted on hearing a prophet of the Lord instead. Micaiah's warning then confirmed that the campaign was not favored by God, yet Jehoshaphat still went with Ahab into the battle.