19 but thus do to them, that they may live, and not die, when they approach the most holy things: Aaron and his sons shall go in and appoint everyone to his service and to his burden;
Numbers 4:19 Cross References - WEB
Numbers 4:15
15 “When Aaron and his sons have finished covering the sanctuary and all the furniture of the sanctuary, as the camp moves forward; after that, the sons of Kohath shall come to carry it; but they shall not touch the sanctuary, lest they die. The sons of Kohath shall carry these things belonging to the Tent of Meeting.