Exodus 28:35

And it shall be upon Aaron to minister,.... That is, the robe before described shall be put upon him, that he might minister in the priest's office, for without this, as well as the other garments, he might not:

and his sound shall be heard when he goeth in unto the holy place before the Lord, and when he cometh out; by means of which the priests would have notice that they might depart, and he be alone in his ministrations; or rather, that the people might know his going out and coming in, and so give themselves up to prayer, while he was offering incense, see Luke 1:9 though the instance of Zacharias is not of an high priest, but of a common priest:

that he die not the Targum of Jonathan adds, with flaming fire. This is added, to make him, and all succeeding priests, careful that this robe, nor any other of the priestly garments, were wanting, when they ministered before the Lord; should any be wanting, it would be highly resented by the Lord: and such an one would be in danger of being cut off by death from the immediate hand of God, as Nadab and Abihu were for offering strange fire to the Lord; for, according to the Jewish writers e, a priest not rightly attired, either with more or fewer garments than he should have, his service was illegal, and he was as a stranger, and his service strange service, unacceptable to God, yea, provoking to him; and so Jarchi on the text says, if he wanted one of these garments, he was guilty of death by the hand of heaven, the immediate hand of God.

e Maimon. Cele Hamikdash, c. 10. sect. 4, 5.