Albert Barnes Commentary Zechariah 3:4

"And he answered and spake unto those that stood before him, saying, Take the filthy garments from off him. And unto him he said, Behold, I have caused thine iniquity to pass from thee, and I will clothe thee with rich apparel." — Zechariah 3:4 (ASV)

And He spoke to those who stood before Him—the ministering angels who had waited on the Angel of THE LORD to do His bidding.

See, I have caused thine iniquity to pass from thee—these are pardoning words, like those of the Lord to David by Nathan: The Lord too hath put away thy sin (2 Samuel 12:13). The promise continues, And clothe thee with change of raiment, that is, garments such as were taken off and reserved for great occasions.

As the filthy garments were not necessarily different from the high priest’s vesture (symbolically defiled through the sins of the people), so these new ones also need be no other than the priestly garments in their purity and freshness. The words imply the condition, not the nature of the vestment.

Cyril explains: "The high priest, having been thus understood to represent the whole people, the filthy garments would be a clear symbol of the wickedness of the people. For, clad as it were with their sins, with the indelible spot of ungodliness, they remained in captivity, subject to retribution, paying the penalty of their unholy deeds. But when God had pity on them, He commanded them to be freed from their defilements and, in a manner, reclothed with justifying grace. He indicates to them the end of their toils. For where remission of sin is, there necessarily follows freedom from the evils brought through sin."

The biblical text further states that a clean mitre should be put upon his head. Cyril comments on this: "This was so that we might understand that the glory of the priesthood always, in a sense, aligns with the condition of the people."

For the boast of the priesthood is the purity of those in their charge. Thus, when the people were in sin, the raiment of the priest also was in a way defiled; so if the people were again approved, pure and bright is the condition of the priesthood, and free its access to God. Thus, the inspired Paul, having ministered the Gospel of Christ to the Gentiles and seeing them advancing in graces, writes, By your boast, brethren, which I have in Christ Jesus (1 Corinthians 15:31), and, my joy and crown (Philippians 4:1).