The careful integration of the Sermon at the Temple throughout the remainder of 3 Nephi provides a means of understanding seemingly obscure parts of the Sermon on the Mount, as has been noted above. But it does something else as well. By quoting His own words so often, Jesus taught His people the central importance of this primary Sermon, which He said (19:8) was to be remembered and used with precision, “nothing varying.” So should it be for us as well.
In this chapter, Jesus next explains that He will go to “other sheep” (16:1) in addition to these people at Bountiful, so that they may all be “one fold and one shepherd” (16:3). He commands the Nephites to write what Jesus has taught them so that it can come forth and all “may be brought to a knowledge of [Christ], their Redeemer” (16:4). The believing Gentiles will be blessed, but the “fullness” of the gospel will be taken from “the unbelieving Gentiles” who commit all kinds of sins. But if they will repent, they shall yet “be numbered among my people” (16:13). Otherwise, they will be “trodden under foot” (16:15), as the salt that has lost its savor (12:13). Jesus then ended this concluding peroration by saying that, in all of this, the words of Isaiah (in Isaiah 52:8–10) “shall be fulfilled,” and he then quoted Isaiah 52:8–10 (see 16:17–20), and was about to leave.
I suspect that Jesus was thinking at that time that He would discuss Isaiah 52:8–10 further on the next day, as He was already planning to come again to these people on the next day (17:3). And indeed, when Jesus will return, He will pick up (in 3 Nephi 20:32–39) exactly where He leaves off here with Isaiah 52:8–10. That text was very important to the Nephites, having been cited by Abinadi back in Mosiah 15:29–31.
But as Jesus was turning to leave thinking He had already overwhelmed them (quoting Isaiah tends to do that to people), Jesus saw that the people were in tears. Moved with deepest compassion, He magnificently stayed on, as we will learn next in 3 Nephi 17–18.
Dana M. Pike, “‘How Beautiful upon the Mountains’: The Imagery of Isaiah 52:7–10 and Its Occurrences in the Book of Mormon,” in Isaiah in the Book of Mormon, ed. Donald Parry and John Welch (Provo: FARMS, 1998), esp. 266–272.
Book of Mormon Central, “Why is the Sermon at the Temple Echoed throughout the Rest of 3 Nephi? (3 Nephi 16:6), KnoWhy 208 (October 13, 2016).”
John W. Welch, “Echoes from the Sermon on the Mount,” in The Sermon on the Mount in Latter-day Scripture, ed. Gaye Strathearn, Thomas A. Wayment, and Daniel L. Belnap (Provo and Salt Lake City, UT: Religious Studies Center, Brigham Young University and Deseret Book, 2010), 314–315; reprinted as “Reusages of the Words of Christ,” Journal of Book of Mormon Studies and Other Restoration Scripture, 22 no. 1 (2013): 63–71.