Numbers 4:18-20

Amplified Bible, Classic Edition

¹⁸ [Since] the tribe of the families of the Kohathites [are only Levites and not priests], do not [by exposing them to the sin of touching the most holy things] cut them off from among the Levites.

¹⁹ But deal thus with them, that they may live and not die when they approach the most holy things: Aaron and his sons shall go in and appoint them each to his work and to his burden [to be carried on the march].

²⁰ But [the Kohathites] shall not go in to see the sanctuary [the Holy Place and the Holy of Holies] or its holy things, even for an instant, lest they die.