King Mosiah allows his sons to leave Zarahemla to preach the word of God to their enemies, the Lamanites. Ammon is captured and brought before King Lamoni. Ammon expresses his desires to live among the Lamanites. The king is impressed with Ammon and asks him to marry one of his daughters. Instead, Ammon asks to be the king’s servant.
Based on Alma 17:20, 23–25.
Alma 17
20 And as Ammon entered the land of Ishmael, the Lamanites took him and bound him, as was their custom to bind all the Nephites who fell into their hands, and carry them before the king; and thus it was left to the pleasure of the king to slay them, or to retain them in captivity, or to cast them into prison, or to cast them out of his land, according to his will and pleasure.
23 And Ammon said unto him: Yea, I desire to dwell among this people for a time; yea, and perhaps until the day I die.
24 And it came to pass that king Lamoni was much pleased with Ammon, and caused that his bands should be loosed; and he would that Ammon should take one of his daughters to wife.
25 But Ammon said unto him: Nay, but I will be thy servant. Therefore Ammon became a servant to king Lamoni. And it came to pass that he was set among other servants to watch the flocks of Lamoni, according to the custom of the Lamanites.
Book of Mormon Videos
The Book of Mormon: Another Testament of Jesus Christ
https://www.churchofjesuschrist.org/study/scriptures/bofm/alma/17.20,23-25