Numbers 4:18–20

18 “Let not the tribe of the clans of the Kohathites be destroyed from among the Levites, 19 but deal thus with them, that they may live and not die when they come near to sthe most holy things: Aaron and his sons shall go in and appoint them each to his task and to his burden, 20 tbut they shall not go in to look on the holy things even for a moment, lest they die.”