Textual: The introductory phrase which is at the head of this chapter is original to the 1830 edition (save the bracketed text marking the chapters covered). Even though the first verse is not properly discourse, it nevertheless is a shift between abridged and cited material. We have the introductory “I, Alma,” that is a clear marker of cited text rather than Mormon’s synopsis. The source text that Mormon is citing for these chapters is at least presented as the holographic writing of Alma, whether or not that was actually the case. We cannot be absolutely certain that Alma wrote is own sermons.
Certainly this introductory paragraph and the nature of the text as a dialog indicates that the original redaction of the sermon is ex post facto. One way or another, this sermon was written down after it was delivered with Alma being the stated and presumed author (though it is not inconceivable that a scribe wrote it for him, such things are known for historical accounts). This tells us that we are probably dealing with a somewhat idealized account of the events rather than a “recording” of the actual discourse. This makes little difference to the import that the discourse has for the modern audience, but it is an important historical consideration.