(Isa. 52:1)
What comes about as a result of exercising the Priesthood is equivalent to putting on “her beautiful garments.”
(Hyrum M. Smith, as quoted in Hoyt W. Brewster, Jr., Doctrine & Covenants Encyclopedia[Salt Lake City: Bookcraft, 1988], 40.)
According to the Lord’s instruction in Leviticus concerning the Day of Atonement, the high priest was to “wash his flesh in water” and then to “put on the holy linen coat,” “linen breeches,” “a linen girdle,” and a “linen mitre” (Lev. 16:4). While wearing these garments, the high priest was to make atonement for himself, the temple, and the people by sacrifice (see Lev. 16:33). During this ceremony, the high priest and priests were instructed on numerous occasions to remove their garments, wash themselves, and wash their clothes (see Lev. 16:23–24, 26, 28).
Such emphasis on garments being kept clean (for example, from the blood of the sacrifices) in connection with the temple and the Day of Atonement may have inspired Jacob to take off his garments and display them before the Nephites, saying, “I pray the God of my salvation that he view me with his all-searching eye; … that the God of Israel did witness that I shook your iniquities from my soul, and that I stand with brightness before him, and am rid of your blood” (2 Ne. 9:44). This theme is further supported by Jacob’s reference to “being clothed with purity, yea, even with the robe of righteousness” (2 Ne. 9:14) and by an Isaiah passage Jacob quotes: “Awake, awake, put on they strength, O Zion; put on thy beautiful garments, O Jerusalem, the holy city; for henceforth there shall no more come into thee the uncircumcised and the unclean” (2 Ne. 8:24, parallel to Isa. 52:1).
(John S. Thompson, Isaiah In The Book of Mormon, ed. Donald W. Parry and John W. Welch [Provo, Utah: Foundation for Ancient Research and Mormon Studies, 1998], 131–32.)