The Levites: Services of Keeping the Charge of the Sanctuary
Source: TTT
Numbers 18:3
And they shall attend to your duties and to all the duties of the Tent; but they must not come near to the furnishings of the sanctuary or the altar, or both they and you will die.
1 Chronicles 23:32
So the Levites were to carry out the responsibilities for the Tent of Meeting and the Holy Place, and, under their brothers the descendants of Aaron, the service of the house of the LORD.