Mormon closes this story and sets up the next. As has been noted previously, when Mormon concludes with a positive or even glowing description, it is typically a setup for the problems that will come later. That is what we will see with verses 6 and 7. The result of Mosiah’s actions are to settle the conflict and to have peace in the land. They therefore prosper.
It is important to understand that while prospering and becoming a large and wealthy people were good, it was a good derived from living the essential Nephite principles. In verses 3, 4 and 5, Mormon reiterates the Nephite principle of equality. Specifically, “every man should esteem his neighbor as himself, laboring with their own hands for their support.” This was true for priests and teachers as well. Even though this principle was prominent in King Benjamin’s speech, and this picture is painted for Benjamin’s son, Mosiah, it is a principle with which Mormon himself was familiar at the end of the Nephite nation. It is an important underlying theme throughout the Book of Mormon.