Numbers 4:20 in the World English Bible
but they shall not go in to see the sanctuary even for a moment, lest they die.”
Context
19 But thus do unto them, that they may live, and not die, when they approach unto the most holy things: Aaron and his sons shall go in, and appoint them every one to his service and to his burden:
20 But they shall not go in to see when the holy things are covered, lest they die.
21 And the LORD spake unto Moses, saying,