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. To this end God had handed over the Levites to them as a gift, to be their assistants (see at Num 3:9 and Num 8:16, Num 8:19). But Aaron and his sons were to attend to the priesthood “with regard to everything of the altar and within the vail” (i.e., of the most holy place, see Lev 16:12). The allusion is to all the priestly duties from the altar of burnt-offering to the most holy place, including the holy place which lay between. This office, which brought them into the closest fellowship with the Lord, was a favour accorded to them by the grace of God. This is expressed in the words, “as a service of gift (a service with which I present you) I give you the priesthood.” The last words in Num 18:7 are the same as in Num 1:51; and “stranger” (zar), as in Lev 22:10.