Redaction: There are two possible meanings to Nephi’s statement that “Jacob spake many more things… at that time.” First, Nephi recorded the only two occasions on which Jacob spoke (his two-day sermon) but gave a condensed version of what Jacob said in those sermons, omitting many details. This hypothesis does not seem likely, however, given the reasonably strong organization and internal coherence of the sermons. It would be hard to see where “many more things” were omitted.
The second possibility, which seems more likely to me, is that Jacob gave a third-day sermon on this same occasion. He has already given carefully organized sermons on two days. The second-day sermon ended with a definite conclusion. But if we hypothesis a possible three-day festival, each day with its own sermon, why didn’t Nephi record it? I hypothesize that the two-day sermon “sufficeth” to meet Nephi’s motives in requesting that sermon in the first place (2 Ne. 6:4); the third-day sermon was on a topic of interest to Jacob but not necessarily to Nephi.
As I have already argued (2 Nephi, Part 1: Context,Chapter 2, “Overview of 2 Nephi”), Nephi started the book of 2 Nephi because he saw it as conceptually different from 1 Nephi. I further argue that the unifying theme of the disparate documents in 2 Nephi is that they deal with material that he considered essential to the cultural and political identity of his people. Jacob’s sermon is a foundational document because it encourages the unity of the lineal Nephites and the adopted “others.” Jacob’s sermon functions as a community building tool. The communal charter of acceptance and adoption into the blessings of Israel is one of the basic definitions of Nephi’s community. It therefore belongs in his treatise where such foundational principles are accumulated.