1 Kings 22:3-4

22:3 The king of Israel said to his servants, “Surely you recognize that Ramoth Gilead belongs to us, though we are hesitant to reclaim it from the king of Syria.” 22:4 Then he said to Jehoshaphat, “Will you go with me to attack Ramoth Gilead?” Jehoshaphat replied to the king of Israel, “I will support you; my army and horses are at your disposal.”

1 Kings 22:6

22:6 So the king of Israel assembled about four hundred prophets and asked them, “Should I attack Ramoth Gilead or not?” They said, “Attack! The sovereign one will hand it over to the king.”