Alma 18:8-10

8 And it came to pass that king Lamoni inquired of his servants, saying: Where is this man that has such great power?

9 And they said unto him: Behold, he is feeding thy horses. Now the king had commanded his servants, previous to the time of the watering of their flocks, that they should prepare his horses and chariots, and conduct him forth to the land of Nephi; for there had been a great feast appointed at the land of Nephi, by the father of Lamoni, who was king over all the land.

10 Now when king Lamoni heard that Ammon was preparing his horses and his chariots he was more astonished, because of the faithfulness of Ammon, saying: Surely there has not been any servant among all my servants that has been so faithful as this man; for even he doth remember all my commandments to execute them.

I wish I could see Lamoni's face and body language. It's fun to imagine though!