The Lamanites [were] a wild and a hardened and a ferocious people; a people who delighted in murdering the Nephites, and robbing and plundering them ... that they might not labor for them with their own hands. Alma 17:13 17:13
After Ammon and king Lamoni had established a church, Lamoni wanted to take Ammon to the land of Nephi and introduce him to his father.
2 And the voice of the Lord came to Ammon saying: Thou shalt not go up to the land of Nephi, for behold, the king will seek thy life; but thou shalt go to the land of Middoni; for behold, thy brother Aaron, and also Muloki and Ammah are in prison.
But God said to Ammon.
Don't visit the land of Nephi, because the king will try to kill you. Instead go rescue your brothers, Aaron, Muloki, and Ammah, who are in prison in the land of Middoni.
So Ammon told Lamoni he couldn't go with him to the land of Nephi.
4 Now Lamoni said unto Ammon: I know, in the strength of the Lord thou canst do all things. But behold, I will go with thee to the land of Middoni; for the king of the land of Middoni, whose name is Antiomno, is a friend unto me; therefore I go to the land of Middoni, that I may flatter the king of the land, and he will cast thy brethren out of prison. Now Lamoni said unto him: Who told thee that thy brethren were in prison?
Lamoni said to Ammon,
I'll go with you to the land of Middoni. Antiomno, the king of Middoni, is my friend. I'll flatter him and he'll let your brothers go.
But who told you your brothers were in prison.
Ammon told him that nobody told him, he just heard it from God.
That was good enough for Lamoni to get his chariot ready. 
So they left for the land of Middoni.
On the way, they ran across Lamoni's father, who was the king of all the land. He said to Lamoni,
Where are you going with this Nephite,
who is the child of a liar?
Lamoni told his father where he was going,
13 And now when Lamoni had rehearsed unto him all these things, behold, to his astonishment, his father was angry with him, and said: Lamoni, thou art going to deliver these Nephites, who are sons of a liar. Behold, he robbed our fathers; and now his children are also come amongst us that they may, by their cunning and their lyings, deceive us, that they again may rob us of our property.
but his father was still angry and said to him,
14 Now the father of Lamoni commanded him that he should slay Ammon with the sword. And he also commanded him that he should not go to the land of Middoni, but that he should return with him to the land of Ishmael.
Kill Ammon with your sword and return to the land of Ishmael.
15 But Lamoni said unto him: I will not slay Ammon, neither will I return to the land of Ishmael, but I go to the land of Middoni that I may release the brethren of Ammon, for I know that they are just men and holy prophets of the true God.
But Lamoni refused,
so his father drew his sword to kill his son.
17 But Ammon stood forth and said unto him: Behold, thou shalt not slay thy son; nevertheless, it were better that he should fall than thee, for behold, he has repented of his sins; but if thou shouldst fall at this time, in thine anger, thy soul could not be saved.
18 And again, it is expedient that thou shouldst forbear; for if thou shouldst slay thy son, he being an innocent man, his blood would cry from the ground to the Lord his God, for vengeance to come upon thee; and perhaps thou wouldst lose thy soul.
Ammon said to him,
You won't kill your son, even though it'd be better for him to die than you, since he has repented and is saved.
If you died now, your soul couldn't be saved.
Lamoni's father said,
Okay I won't kill my son.
I'll kill you instead.
But Ammon smote his arm so he couldn't use it.
24 Now when Ammon saw that he had wrought upon the old king according to his desire, he said unto him: If thou wilt grant that my brethren may be cast out of prison, and also that Lamoni may retain his kingdom, and that ye be not displeased with him, but grant that he may do according to his own desires in whatsoever thing he thinketh, then will I spare thee; otherwise I will smite thee to the earth.
Lamoni's father begged Ammon not to kill him, offering him half of his kingdom. Ammon said,
I'll kill you unless you get my brothers out of prison.
26 And when he saw that Ammon had no desire to destroy him, and when he also saw the great love he had for his son Lamoni, he was astonished exceedingly, and said: Because this is all that thou hast desired, that I would release thy brethren, and suffer that my son Lamoni should retain his kingdom, behold, I will grant unto you that my son may retain his kingdom from this time and forever; and I will govern him no more --
27 And I will also grant unto thee that thy brethren may be cast out of prison, and thou and thy brethren may come unto me, in my kingdom; for I shall greatly desire to see thee. For the king was greatly astonished at the words which he had spoken, and also at the words which had been spoken by his son Lamoni, therefore he was desirous to learn them.
Lamoni's father said,
I'll get your brothers out of prison, and Lamoni can retain his kingdom.
28 And it came to pass that Ammon and Lamoni proceeded on their journey towards the land of Middoni. And Lamoni found favor in the eyes of the king of the land; therefore the brethren of Ammon were brought forth out of prison.
29 And when Ammon did meet them he was exceedingly sorrowful, for behold they were naked, and their skins were worn exceedingly because of being bound with strong cords. And they also had suffered hunger, thirst, and all kinds of afflictions; nevertheless they were patient in all their sufferings.
30 And, as it happened, it was their lot to have fallen into the hands of a more hardened and a more stiffnecked people; therefore they would not hearken unto their words, and they had cast them out, and had smitten them, and had driven them from house to house, and from place to place, even until they had arrived in the land of Middoni; and there they were taken and cast into prison, and bound with strong cords, and kept in prison for many days, and were delivered by Lamoni and Ammon.
So Ammon and Lamoni continued on their journey to the land of Middoni.
When they arrived the king liked Ammon so much that he let his brothers out of prison.