I Chronicles 25:9

First Chronicles 25 records David's organization of the temple musicians into twenty-four priestly divisions, drawing from the sons of Asaph, Heman, and Jeduthun, who were set apart to prophesy with harps, lyres, and cymbals under the direction of the king. Each division consisted of twelve musicians, and lots were cast impartially so that teacher and student alike received equal assignments. This careful arrangement of sacred music reflected David's conviction that worship in the temple should be ordered, Spirit-led, and led by skilled and consecrated servants.