Shemot 40:15

15 And thou shalt anoint them, as thou didst anoint their av, that they may minister unto Me in the kohen’s office: for their anointing shall surely be for them a kehunat olam throughout their dorot.

Shemot 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.

Shemot 40:15 In-Context

13 And thou shalt dress Aharon with the Bigdei Hakodesh, and anoint him, and set him apart as kodesh; that he may minister unto Me in the kohen’s office.

14 And thou shalt bring near his banim, and dress them with kuttanot:

15 And thou shalt anoint them, as thou didst anoint their av, that they may minister unto Me in the kohen’s office: for their anointing shall surely be for them a kehunat olam throughout their dorot.

16 Thus did Moshe; according to all that Hashem commanded him, so did he.

17 And it came to pass in the first month in the second year, on the first day of the month, that the Mishkan was erected.