1 Kings 22:29

So the king of Israel and Jehoshaphat the king of Judah went up to Ramoth–gilead.

Cross-reference

In 1 Kings 22:2-9, the kings consult prophets and decide to attack — verse 29 carries out that decision.

2 Chronicles 18:28 records the same event — the kings going up to Ramoth-gilead — as a direct parallel account.