Garold Davis notes that in view of the significance of Isaiah in the Book of Mormon, it is perhaps fitting that Moroni should quote from Isaiah as part of his final exhortation and farewell: "And again I would exhort you that ye would come unto Christ, and lay hold upon every good gift, and touch not the evil gift, nor the unclean thing [from Isaiah 52:11]. And awake, and arise from the dust, O Jerusalem; yea, and put on thy beautiful garments, O daughter of Zion [from Isaiah 52:1]; and strengthen thy stakes and enlarge thy borders forever [from Isaiah 54:2], that thou mayest no more be confounded, that the covenants of the Eternal Father which he hath made unto thee, O house of Israel, may be fulfilled" (Moroni 10:30-31).
It once again should be emphasized that the Isaiah passages in the Book of Mormon are not unnecessary duplications of the biblical Isaiah. Rather, they are an inspired, integral part of that sacred text. Although the Book of Mormon Isaiah makes significant corrections to the biblical Isaiah, the greater value lies, first, in the contextual setting [or pattern] in which the doctrines of the covenant of Christ's atoning sacrifice, the prophesied scattering of Israel, and the restoration of the house of Israel in the last days through the instrumentality of the gentiles receive their full and proper emphasis; and, second, in the rich and detailed interpretations given us through the commentaries of Lehi, Nephi, Jacob, Abinadi, and the Savior. [Garold N. Davis, "Pattern and Purpose of the Isaiah Commentaries in the Book of Mormon," in Davis Britton ed. Mormons, Scripture, and the Ancient World, F.A.R.M.S., pp. 301-302] [See the commentary on Words of Mormon 1:5]
Note* To Moroni's words in Moroni 10:30-31 can be added those in Mormon 8:22-23:
For the eternal purposes of the Lord shall roll on, until all his promises shall be fulfilled. Search the prophecies of Isaiah. Behold, I cannot write them. Yea, behold I say unto you, that the saints who have gone before me who have possessed this land, shall cry, yea, even from the dust will they cry unto the Lord; and as the Lord liveth he will remember the covenant which he hath made with them. (Mormon 8:22-23)
[Alan C. Miner, Personal Notes]