NET

15 The musicians, the descendants of Asaph, manned their posts, as prescribed by David, Asaph, Heman, and Jeduthun the king’s prophet. The guards at the various gates did not need to leave their posts, for their fellow Levites made preparations for them.

Darby

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 doorkeepers were at every gate; they had not to depart from their service, for their brethren the Levites prepared for them.

KJV

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.