Numbers 4:15, 19

And when Aaron and his sons have finished covering the sanctuary and all the furnishings of the sanctuary, when the camp is set to go, then the sons of Kohath shall come to carry them; but they shall not touch any holy thing, lest they die. “These are the things in the tabernacle of meeting which the sons of Kohath are to carry.

but do this in regard to them, that they may live and not die when they approach the most holy things: Aaron and his sons shall go in and appoint each of them to his service and his task.