2 Chronicles 20:14
Then upon Jahaziel the son of Zechariah, the son of Benaiah, the son of Jeiel, the son of Mattaniah, a Levite of the sons of Asaph, came the Spirit of the LORD in the midst of the congregation; Then upon Jahaziel the son of Zechariah, the son of Benaiah, the son of Jeiel, the son of Mattaniah, a Levite of the sons of Asaph, came the Spirit of the LORD in the midst of the congregation;
Judah had gathered to humble themselves and seek help from God when the Spirit of the Lord came upon Jahaziel right in the midst of the congregation. Jahaziel was a Levite of the sons of Asaph. Through him God spoke to King Jehoshaphat and to all the people, telling them not to fear the enemy's great numbers. The reason given was that the battle was not theirs but God's.
They were directed to stand firm and witness the deliverance and salvation of the Lord. They were assured that the Lord would be with them. Trusting this message, Judah went out to battle praising God for the victory.