In context
19Do this for them so that they may live and not die when they approach the most holy things: Aaron and his sons shall go in and assign each of them to his task and to what he is to carry. 20But they must not go in to look at the holy things even for a moment, or they will die.” 21Yahweh spoke to Moses. He said, 22“Take a census of the descendants of Gershon as well, by their ancestral houses, by their clans. 23You shall number them from thirty years old to fifty years old, everyone who enters to serve in the work of the tent of meeting.
