Jerald Simon notes that in Jesus' covenant discourse in 3 Nephi 20-23 he twice commands his faithful listeners to "search Isaiah" (see 3 Nephi 20:11; 23:11). The people had felt the prints in his hands and feet and had thrust their hands into his side. They were the worthy ones who had been "spared because" they "were more righteous than" the others (3 Nephi 9:13). Christ was the living embodiment of the Abrahamic covenant. Christ was not only the Master but the Master teacher of Isaiah. These disciples truly knew what it meant to "come unto Christ."
Jesus mentions Moses' writing of a future prophet and explains how his coming fulfilled those words. He teaches the Nephites that they are "children of the prophets" and "children of the covenant" (3 Nephi 20:25-26). He also speaks of the time when Isaiah's words will be fulfilled, regarding the scattering, the gathering, the role of the Gentiles, a marvelous work, the Prophet Joseph Smith, the coming forth of the Book of Mormon, and other themes, interspersing in his discourse almost every verse from Isaiah 52 and 54.
As if setting bookends to hold the covenant doctrine in place, Jesus, who quoted Isaiah more than he quoted any other prophet while in his mortal ministry, instructs the Nephites at both the introduction and conclusion of his covenant discourse to "search Isaiah.
Christ clearly desired there be no misunderstanding regarding his covenant discourse as evidenced by the charge given to Mormon while he was abridging the account of the Savior's visit. At the conclusion of 3 Nephi, Mormon recorded: "I say unto you that when the Lord shall see fit, in his wisdom, that these sayings shall come unto the Gentiles according to his word, then ye may know that the covenant which the Father hath made with the children of Israel concerning their restoration to the lands of their inheritance, is already beginning to be fulfilled" (3 Nephi 29:1). Indeed, Mormon later emphasizes that Jesus had commanded him to restate this theme: "hearken, O ye Gentiles, and hear the words of Jesus Christ, the Son of the living God, which he hath commanded me that I should speak concerning you . . . that ye may be numbered with my people who are of the house of Israel" (3 Nephi 30:1-2). [Jerald F. Simon, "Researching Isaiah Passages in the Book of Mormon," in Covenants Prophecies and Hymns of the Old Testament, pp. 218-219]