Charles Spurgeon Commentary 1 Chronicles 15:27-28

"And David was clothed with a robe of fine linen, and all the Levites that bare the ark, and the singers, and Chenaniah the master of the song [with] the singers: and David had upon him an ephod of linen. Thus all Israel brought up the ark of the covenant of Jehovah with shouting, and with sound of the cornet, and with trumpets, and with cymbals, sounding aloud with psalteries and harps." — 1 Chronicles 15:27-28 (ASV)

David himself, while playing on his harp, leaping and dancing through the intensity of joy which filled his soul.