Bible Search Cross Reference 2 Chronicles 35:15. And the singers the sons of Asaph were in their place, according to the commandment of David, and Asaph, and Heman, and Jeduthun the king's seer; and the porters waited at every gate; they might not depart from their service; for their brethren the Levites prepared for them.


http://qbible.com/references/2-chronicles/35-15.html