2 Chronicles 20:19-21 And the Levites stood up to praise the Lord God of Israel with a loud voice on high. And they rose early in the morning, and went forth into the wilderness of Tekoa: and as they went forth, Jehoshaphat stood and said, Hear me, O Judah, and ye inhabitants of Jerusalem, believe in the Lord your God, so shall ye be established; believe his prophets, so shall ye prosper. And when he had consulted with the people, hr appointed singers unto the Lord, and that should praise the beauty of holiness, as they went out before the army, and to say, Praise the Lord; for his mercy endureth for ever.
In the face of a battle against a massive enemy army, Jehoshaphat believed in the Lord and in His Word. And he encouraged the people to believe God and His prophets. If they do, then they will be established and prosper. Because of his faith he sent ahead singers to praise the Lord. He sent the singers into battle ahead of the army, for the battle belonged to the Lord. Jehoshaphat did not know ahead of time what God was going to do, but he praised God anyway simply because He is good and His steadfast love endures.
The slaughter that followed was so complete that it took Judah three days to gather the spoil. Jehoshaphat heard the Word, believed it, then praised the Lord, and after that saw what God had done. This sequence happens to us in the same way daily: we hear the Gospel, we believe it for the Spirit plants faith in the hearing, then we respond with continual praise and thanksgiving, and after that we see the finished work of Christ (sin, death, and the devil are utterly destroyed). This experience is not a one-time event, but it is weekly and daily for us. Our whole life is filled with praise.