Numbers 4:19
But thus do unto them, that they may live, and not die, when they approach unto the most holy things: Aaron and his sons shall go in, and appoint them every one to his service and to his burden: But thus do unto them, that they may live, and not die, when they approach unto the most holy things: Aaron and his sons shall go in, and appoint them every one to his service and to his burden:
Aaron and his sons were to go in and appoint every Levite to his specific service and to his burden when approaching the most holy things, that they might live and not die. The appointment was to be made beforehand, directing each man to his particular duty so the work would be carried out safely. The service and burden thus assigned was the sacred work of carrying the most holy things. It included setting up, taking down, carrying, and caring for the tabernacle and its furnishings. The arrangement shows that God required order in handling the sanctuary through careful division of sacred service among appointed workers, each responsible for the task given to him rather than acting by individual choice.