Aaron begins to teach them from the scriptures. He does this not only because the scriptures are where the prophets have explained these things, but because the order of the Nehors does accept some set of scriptures. It is possible that they only considered the brass plates scripture, holding the rest of the writings since Nephi as part of that set of information where the “fathers” did not know of “which they spake.”
We know that when Abinadi was before the court of King Noah brass plate scriptures were used as part of the test against Abinadi. Thus what Aaron does is begin to open the scriptures that they accept, to show in them the doctrine that they do not accept. The result of this preaching is that the people are angry. They are certainly not repentant, and their turn their anger into a verbal assault on Aaron.
Textual: Mormon makes an interesting editorial choice here. Mormon’s typical editorial process has been to take a speech from his source plates where the subject of the speech is important to his message, and present the speech in its entirety. That does not happen here. We have just verse 9 as Mormon’s synopsis of the discourse. Was this discourse missing from the source, or did Mormon choose to condense it dramatically?
Of course we cannot know all that was on Mormon’s source plates, but it may be suggested that the evidence in this case points to Mormon’s choice rather than necessity. It would have been necessary to synopsize if the original account did not have the full discourse, but if it were there, then this is a conscious choice. What evidence do we have that Mormon’s source material contained the full discourse?
The first hint is the exchange between the Amalekite and Aaron. As noted, the identification of the man as an Amalekite must have had some more important role in the plate text. The conversation between the two is precisely the form we expect of recorded dialog, and the similarity to the issues and format of the confrontation between Zeezrom and Alma and Amulek suggests that this may have been a copy from the plate text, though ancient authors were not above creating conversations which they could not have heard.
The strongest suggestion that Mormon chose to leave out material at this point is the text that comes later. We get a much longer discourse of Aaron before Lamoni’s father. Since Ammon is not there, it must come from Aaron’s record, and having that much of the record in one case, but not the other is not consistent. It would appear that Mormon simply decided to leave this sermon out. Why?
First, it is redundant information. While Aaron may have been a righteous man and a good speaker, the information that Mormon synopsizes for us is material that has recently been covered by Alma and Amulek. Mormon controls his text, and he understands that this information has already been presented. What Mormon is interested in here is the bare bones history that will get him into the tale of Aaron so that he can give us the discourse with the father of Lamoni.