3 Nephi 9:1-10 There was a Voice Heard

Who is speaking?
Search: In verse 10, it mentions King Jacob. We recently read about him. What do we know about him from earlier chapters? Use the footnotes and index if you don't remember. Why was his city destroyed? Do we know anything about these other cities that were destroyed? Use the footnotes and index to see if any of them are mentioned elsewhere in the Book of Mormon.