And the singers the sons of Asaph were in their place,.... In the court of the priests, singing and playing on their instruments while the sacrifices were offering:
according to the commandment of David, and Asaph, and Heman, and Jeduthun the king's seer; the same with Ethan; and everyone were seers, as Jarchi interprets it, that is, the three last:
and the porters waited at every gate; such of the Levites as were in, that post and office:
they might not depart from their service; to let people in and out, that came for their passover lamb, and share in their other offerings:
for their brethren the Levites prepared for them; because they were not at leisure to prepare for themselves.