During the first nine verses of this chapter Mosiah struggles with his people trying to figure out how best to select a successor for the throne. It is not until verse 11 that Mosiah tells the Nephites what the solution should be. However, he doesn't mention that this came as a revelation from the Lord. It is clear over in Helaman 4:22 that we learn that the Lord commanded Mosiah to no longer have kings to rule over the people. Instead they are to have a system of judges set up over the people.
We begin this chapter with Mosiah trying to get advice from the people as to the best method of selecting a successor.
It is interesting that Mosiah's son, Aaron, was very popular among the people but that didn't solve the problem. Mosiah explains why.