After this, the Moabites and Ammonites with some of the Meunites came to make war on Jehoshaphat. ... Alarmed, Jehoshaphat resolved to inquire of the LORD, and he proclaimed a fast for all Judah. The people of Judah came together to seek help from the LORD; indeed, they came from every town in Judah to seek him.
Read all of 2 Chronicles 20 NIV