Albert Barnes Commentary 1 Kings 22:5

"And Jehoshaphat said unto the king of Israel, Inquire first, I pray thee, for the word of Jehovah." — 1 Kings 22:5 (ASV)

Jehoshaphat, with characteristic piety (1 Kings 22:43), takes advantage of his position as Ahab’s friend and ally to suggest an inquiry of the Lord (Yahweh) before the expedition is undertaken. To prevent Ahab from agreeing in word only while delaying the actual inquiry, he asks to have the prophets called in at once: “today.”