In the tent of meeting outside the curtain that is before the testimony, Aaron and his sons are to arrange it from evening to morning before the Lord. This is to be a lasting ordinance among the Israelites for generations to come.
“Bring with you your brothers, the tribe of Levi, the tribe of your father, so that they may join with you and minister to you while you and your sons with you are before the tent of the testimony.
You will say to them, ‘This is the offering made by fire which you must offer to the Lord: two unblemished lambs one year old each day for a continual burnt offering.
So if perfection had in fact been possible through the Levitical priesthood – for on that basis the people received the law – what further need would there have been for another priest to arise, said to be in the order of Melchizedek and not in Aaron’s order?