2Chr 20:21-22, 21…he appointed singers unto the LORD, and that should praise the beauty of holiness, …Praise the LORD; for his mercy endureth for ever. 22 And when they began to sing and to praise, the LORD set ambushments against the children of Ammon, Moab, and mount Seir, which were come against Judah; and they were smitten.
Jehoshaphat considered it an important task to meticulously appoint singers unto the Lord, the most prominent to lead the service of praise. He picked the words and the form of language to be used in the songs among other matters. Casual handling of this task would not be encouraged lest anyone should die as in the days of David when Uzzah wrongly handled the ark of the covenant and died.
God was to be worshiped on two counts, and in this order. 1. To praise Him for who He is (praise the beauty of the glorious holiness of God, whose beauty lies in His holiness). 2. To praise Him for His ways and works (for His mercy endureth for ever). That is quality worship. Their praise moved God, and He set an ambush on their enemies. Quality praise moves God.