John Gill Commentary Numbers 18:5

"And ye shall keep the charge of the sanctuary, and the charge of the altar; that there be wrath no more upon the children of Israel." — Numbers 18:5 (ASV)

And you 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 incense, the shewbread table, and candlestick:

and the charge of the altar ;
of burnt offering, which stood in the court of the tabernacle:

that there be no wrath any more upon the children of Israel :
as had been upon Korah and his company, (Numbers 16:32Numbers 16:33) , and as afterwards came on Uzziah, (2 Chronicles 26:19–21) .