1 Kings 22:12
And all the prophets prophesied so, saying, Go up to Ramoth-gilead, and prosper: for the LORD shall deliver it into the king’s hand. And all the prophets prophesied so, saying, Go up to Ramoth-gilead, and prosper: for the LORD shall deliver it into the king’s hand.
The saying stands in Ahab's quarrel with Micaiah, toward whom Ahab was hostile because Micaiah prophesied evil and not good against him. At that moment four hundred prophets spoke with one voice, urging Ahab to go up to Ramoth-gilead and assuring him that the Lord would deliver it into the king's hand.
That confident assurance was false, for Micaiah warned that Israel would be scattered and that Heaven did not favor the kings' plan. Ahab and Jehoshaphat ignored his warning and went into battle together, where Ahab died, fulfilling Micaiah's word.