Numbers 4:19-21

New Revised Standard Version Catholic Edition

¹⁹ This is how you must deal with them in order that they may live and not die when they come near to the most holy things: Aaron and his sons shall go in and assign each to a particular task or burden. ²⁰ But the Kohathites^[a] must not go in to look on the holy things even for a moment; otherwise they will die.

The Gershonites and Merarites

²¹ Then the Lord spoke to Moses, saying: