They might not depart - The singers and porters remained at their posts, while other Levites sacrificed for them and brought them their share of the lambs.
Related Commentaries of 2 Chronicles 35:15
2 Chronicles 35:15
15 And the singers the sons of Asaph were in their place,e 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.