Redaction: After the carefully crafted ending comes a moral. Its author may be either Nephi or Mormon; but as I read the text from here to the end of the chapter, it seems more reasonable to ascribe it to Mormon.
First, even though Mormon does not specifically identify himself, verse 19 states: “Therefore for this time I make an end of my sayings.” Nephi still has a marvelous story to tell, which begins in the next chapter. Almost certainly, he would have continued directly from the people’s praise into the Savior’s ministry. Second, inserted text has characterized Mormon’s earlier editorial process (Mosiah 1:8–9; Alma 3:9–10, 11:21, 12:19).
Mormon understands that this part of Nephi’s record proved the prophesied coming of the Atoning Messiah. Mormon emphasizes the fulfillment of the scriptures—not just Nephi’s prophecy but those by all of the prophets.