Charles Ellicott Commentary 2 Kings 3:12

"And Jehoshaphat said, The word of Jehovah is with him. So the king of Israel and Jehoshaphat and the king of Edom went down to him." — 2 Kings 3:12 (ASV)

The king of Israel and Jehoshaphat. — All the versions except the Targum add, “the king of Judah.” Jehoshaphat said what follows either based on Elijah’s reputation or because the news of Elisha’s succession had already reached Judah.

The proper names, Shaphat and Jehoshaphat, are identical (He judges, i.e., Jah judges). (Compare Ahaz and Jehoahaz.)

Went down to him. — From the royal tents, which were probably pitched on high ground, so as to overlook the camp. The three kings go to consult the prophet as ordinary people might do. This shows how highly he was regarded. Keil says they were humbled by misfortune.