And the singers the sons of Asaph were in their place. — “At their post” or station (1 Chronicles 23:28). The “sons” of Heman and Jeduthun are omitted for brevity.
According to the commandment... king’s seer. — Comp. 1 Chronicles 25:1-6.
They might not depart. — Rather, they had no need to depart from their service (i.e., to leave their posts), in order to prepare their own passover and the subsequent meals, “for their brethren the Levites had prepared for them,” and brought it to them at their several stations.