Both kings, Lamoni and his unnamed father, had a lot of power, and they were used to wielding that power. Generally, they seemed to be quite deferential toward one other. However, Lamoni’s father was suspicious of Ammon as a Nephite (20:13) and was angry at his son for refusing his orders. He drew his sword and was about to kill his own son. In the ancient world, an ordinary father could kill his son with impunity. This right is known as patria potestas (the power of a father), which in most ancient civilizations gave the father the right to kill his offspring for any reason. Under such circumstances, the father could not be accused of homicide or punished by the society. After all, a father was the king in his own family. If the father also happened to be king of the land who controlled the life of all his subjects, he was twice over the king in this situation.
In our day, this event might strike us as odd. Why would king Lamoni’s father threaten to kill his own son simply because he had been offended that the son had not attended a great feast thrown by the father. Because Lamoni’s father was “king over all the land,” the feast may have been an extremely important celebration for political and religious purposes. Lamoni’s absence from an important kingly feast may have been regarded as dishonor and high disrespect, if not an act of high treason.