And they shall keep thy charge, and the charge of all the tabernacle: only they shall not come nigh the vessels of the sanctuary and the altar, that neither they, nor ye also, die. (Numbers 18:3)
They were the appointed guardians of the sanctuary.
Not come nigh.
This would not refer to the Kohathites (ch. 4:15), but only to the other Levites. The Kohathites were not to handle the vessels when uncovered, nor even to look upon them (ch. 4:19, 20). This prohibition also included the brazen altar Ex. 29:37) as well as the altar of incense, for both were “most holy.”
The vessels.
Literally, “the furniture.” The word translated “vessels” includes all the sacred vessels and furnishings of the sanctuary.