Exodus 40:15

15 and anoint them, as you anointed their father, that they may serve me as priests: and their anointing shall admit them to a perpetual priesthood throughout all generations to come.

Exodus 40:15 Meaning and Commentary

Exodus 40:15

And thou shall anoint them as thou didst anoint their
father
For Aaron was first anointed, and then his sons:

that they may minister unto me in the priest's office;
which they might not do before their anointing, though separated for it, and called unto it:

for their anointing shall surely be an everlasting priesthood
throughout their generations;
that is, this ceremony of anointing was to be used in all ages at the investiture of the high priest with his office, until the Messiah should come, who would put an end to the Aaronic priesthood; for not common priests, only the successors of the high priest, were anointed in later times; this present unction serving for all the priests that should follow in successive generations, so long as the priesthood continued.

Exodus 40:15 In-Context

13 and put on Aaron the sacred vestments, and you shall anoint him and consecrate him, so that he may serve me as priest.
14 You shall bring his sons also and put tunics on them,
15 and anoint them, as you anointed their father, that they may serve me as priests: and their anointing shall admit them to a perpetual priesthood throughout all generations to come.
16 Moses did everything just as the Lord had commanded him.
17 In the first month in the second year, on the first day of the month, the tabernacle was set up.