Ammon had established sufficient common grounds that he could begin to answer the question that Lamoni had asked about how Ammon knew the king’s thoughts. The answer was that Jehovah is in heaven and looks down upon humankind. It is Jehovah who knows “all the thoughts and intents of the heart,” since Jehovah was their creator.
Lamoni understood that his question had been answered, but only partially. Jehovah knew his thoughts, but how did Ammon? Thus Lamoni asks if Ammon was sent by Jehovah. The implication may have been that Ammon might have been one of the angels that Ammon declared were in heaven with God. That hypothesis is perhaps confirmed in Ammon’s response in the next verse.