Exodus 28:43

And they shall be upon Aaron and upon his sons
Not the linen breeches only, but all the other garments:

when they come into the tabernacle of the congregation;
even into that part of it where the people assembled, the court of the tabernacle, and where stood the altar of burnt offering, on which they offered the sacrifices of the people, but never without the priestly garments on:

or when they came near unto the altar to minister in the holy place;
at the altar of incense which stood there; or when they came to trim the lamps of the candlestick, and set the shewbread on the table, and take away the old, which candlestick and shewbread table were both in the holy place,

that they bear not iniquity and die;
be guilty of sin in not having their priestly garments on in time of service, and so bear the punishment of it and die for it; the Targum of Jonathan adds, with flaming fire, with fire from heaven, such as Nadab and Abihu were afterwards consumed with; an high priest that had not the eight garments on, or a common priest that had not his four garments, his service was illegal and rejected, and he was guilty of death by the hand of heaven, as Maimonides ^F19 says; that is, he was deserving of immediate death from the hand of God, and might expect it:

it shall be a statute for ever unto him, and his seed after him;
as long as the Aaronic priesthood continued, until Christ should arise, made an high priest, not after the order of Aaron, but after the order of Melchizedek, and should put an end to the priesthood of the former, by answering and fulfilling all the types and shadows of it; this respects all that is said in this chapter concerning the vestments of the priests, one and another.