2 Chronicles 18:9

And the king of Israel and Jehoshaphat king of Judah sat either of them on his throne, clothed in their robes, and they sat in a void place at the entering in of the gate of Samaria; and all the prophets prophesied before them.

Cross-reference

2 Chronicles 18:29 Historical context

2 Chronicles 18:29 continues the story: Ahab tells Jehoshaphat to keep his robes while he disguises — directly connected to the seating scene.

1 Kings 22:10-12 adds the detail of Zedekiah's iron horns and the unanimous false prophecy — expanding the scene.