TSK · Exodus 29:9

In the Tent of Meeting, outside the veil which is before the testimony, Aaron and his sons shall keep it in order from evening to morning before Yahweh: it shall be a statute forever throughout their generations on the behalf of the children of Israel.

"You shall make coats for Aaron's sons, and you shall make sashes for them and you shall make headbands for them, for glory and for beauty.

You shall anoint them, as you anointed their father, that they may minister to me in the priest's office. Their anointing shall be to them for an everlasting priesthood throughout their generations."

You shall not go out from the door of the Tent of Meeting seven days, until the days of your consecration are fulfilled: for he shall consecrate you seven days.

and that he has brought you near, and all your brothers the sons of Levi with you? and do you seek the priesthood also?

to be a memorial to the children of Israel, to the end that no stranger, who isn't of the seed of Aaron, comes near to burn incense before Yahweh; that he not be as Korah, and as his company: as Yahweh spoke to him by Moses.

and it shall be to him, and to his seed after him, the covenant of an everlasting priesthood; because he was jealous for his God, and made atonement for the children of Israel.'"

The man Micah had a house of gods, and he made an ephod, and teraphim, and consecrated one of his sons, who became his priest.

Nobody takes this honor on himself, but he is called by God, just like Aaron was.

Now if there was perfection through the Levitical priesthood (for under it the people have received the law), what further need was there for another priest to arise after the order of Melchizedek, and not be called after the order of Aaron?