Samuel’s message of repentance was not completely rejected. There were those who did hear, and repent. Those people sought Nephi to be accepted into the gospel and be baptized. This indicates that Nephi was well enough known that he would be the logical one to go to. Such renown further highlights the desperation of the Gadianton leaders who had intended to kill Nephi. They were dealing with a man who was well-known, and then became even more well known through the miraculous discovery of the murderer of the chief judge.
Textual: The current chapter break did not exist in the plates, but there is a division here in the type of material we have. At the end of our chapter 15 we have the conclusion of the inserted record of the preaching of Samuel the Lamanite. Mormon now returns to his own concluding narrative. This is a point at which he has made a chapter break in other chapters. In this chapter his intent is not simply the entry of Samuel’s words, but the aftermath of the speech. Since these events are just as important as the words, Mormon combines them without creating the chapter break.