I Chronicles 15-16
"Seek the Lord and His strength; seek His face continually, remember His wonderful deeds which He has done" (16:11-12). After the tragedy of Uzzah, David took great care to consecrate the priests and Levites according to the Law. He then instructed them to organize themselves musically, as the chief worshipers of Israel. They appointed singers (and singing-teachers, like Chenaniah, v22) and musicians to play harps, lyres, cymbals, etc.
Israelite worship was chiefly group-worship, through sacrifice and music (psalms). Used by every generation, the psalms are precious as our guides for confession, repentance, thanksgiving, and praise.