Curiosity: To Witness the offering in the Holy of Holies
Source: Nav
Numbers 4:19, 20
In order that they may live and not die when they come near the most holy things, do this for them: Aaron and his sons are to go in and assign each man his task and what he is to carry. / But the Kohathites are not to go in and look at the holy objects, even for a moment, or they will die.”