Jamieson, Fausset and Brown on Zechariah 3:4

4. those that stood before him--the ministering angels (compare the phrase in 1Ki 10:8; Da 1:5).

Take away the filthy garments--In Zec 3:9 it is "remove the iniquity of that land"; therefore Joshua represents the land.

from him--literally, "from upon him"; pressing upon him as an overwhelming burden.

change of raiment--festal robes of the high priest, most costly and gorgeous; symbol of Messiah's imputed righteousness (Mt 22:11). The restoration of the glory of the priesthood is implied: first, partially, at the completion of the second temple; fully realized in the great High Priest Jesus, whose name is identical with Joshua (He 4:8), the Representative of Israel, the "kingdom of priests" (Ex 19:6); once clad in the filthy garments of our vileness, but being the chosen of the Father (Is 42:1; 44:1; 49:1-3), He hath by death ceased from sin, and in garments of glory entered the heavenly holy place as our High Priest (He 8:1; 9:24). Then, as the consequence (1Pe 2:5), realized in the Church generally (Lu 15:22; Re 19:8), and in Israel in particular (Is 61:10; compare Is 3:6; 66:21).