Numbers 18:5 (BSB)

And you shall attend to the duties of the sanctuary and of the altar, so that wrath may not fall on the Israelites again.

From Numbers 18. Also in the ESV.

Commentary on Numbers 18:5

• John Calvin (Reformed), Calvin's Commentaries on Numbers 18:5: 5. And ye shall keep the charge. He again exhorts the priests to be diligent in the performance of their office, with the addition of a denunciation of punishment if they failed in zeal and earnestness. Nor does He now threaten them alone, but the whole people; neither does this contradict the foregoing declaration, inasmuch as the common fault of all by no means lightened theirs.
• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Numbers 18:1-7: The coherence of this chapter with that foregoing is very observable. I. The people, in the close of that chapter, had complained of the difficulty and peril that there were in drawing near to God, which put them under some dreadful apprehensions that the tabernacle in the midst of them, which they hoped would have been their joy and glory, would rather be their terror and ruin.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Numbers 18:5: And ye shall keep the charge of the sanctuary,.... That is, the priests, Aaron and his sons; the high priest was to keep the charge of the most holy place particularly, and do what was to be done in that on the day of atonement; and the common priests to keep the charge of the holy place, and do everything relating to the altar of...
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Numbers 18:5-7: Num 18:5-7 The charge of the sanctuary (i.e., the dwelling) and the altar (of burnt-offering) devolved upon Aaron and his sons, that the wrath of God might not come again upon the children of Israel (see Num 8:19), - namely, through such illegal acts as Nadab and Abihu (Lev 10:2), and the company of Korah (Num 16:35), had committed.