Numbers 18:3

And they shall keep thy charge, and the charge of all the tabernacle,.... That is, the Levites, whatever Aaron and his sons, the priests, should charge them to do, or commit to their care and charge, that they should observe; as to watch and keep out all unfit persons, to take down and set up the tabernacle when needful, c.

only they shall not come nigh the vessels of the sanctuary as the ark and mercy seat in the holy of holies, the shewbread table, and candlestick in the holy place; wherefore when these were removed from place to place in journeying, they were covered, that they might not touch them as they carried them:

and the altar; both of incense and burnt offering, on neither of which might they offer:

that neither they nor you also die: the priests for suffering them to meddle with things that did not belong to them, and the Levites for intruding themselves.