Numbers 18:3

And they shall keep thy charge, observe and do those things which they were directed to do by the priest, and the charge of all the Tabernacle, in the matter of transporting the Tabernacle and its appointments and performing such other offices as were connected therewith; only they shall not come nigh the vessels of the Sanctuary, those inside the Tabernacle, and the altar, of incense, that neither they, nor ye also, die; for every person that approached these without proper command and authority risked immediate death, as the people had now repeatedly seen.