2 Chronicles 5:13-14 NKJV
Indeed it came to pass, when the trumpeters and singers were as one, to make one sound to be heard in praising and thanking the Lord, and when they lifted up their voice with the trumpets and cymbals and instruments of music, and praised the Lord, saying: "For He is good, for His mercy endures forever," that the house, the house of the Lord, was filled with a cloud, so that the priests could not continue ministering because of the cloud; for the glory of the Lord filled the house of God.
In 1 Chronicles 16 we learned that people were assigned to thank God for His mercy on a daily basis. Here in 2 Chronicles 5 we read about the celebration that took place when the ark of the covenant was brought into the temple Solomon built. When the praise and worship leaders lifted their voice as the instruments played, they praised the Lord and said "For He is good, for His mercy endures forever." The house of the Lord was filled with a cloud and God's presence was so thick in the room until the priests had to pause. They were unable to continue what they were doing because of the awesome presence of God. It is obvious that the Jews learned to value God's mercy as they made mention of it consistently during their worship.