Mosiah 20:16 - 20:20
Mosiah 20:16 And now Limhi had heard nothing concerning this matter; therefore he said: I will search among my people and whosoever has done this thing shall perish. Therefore he caused a search to be made among his people.
Limhi was ignorant of this event concerning the kidnappings. He told the king that he would search among his people and if he found the kidnappers, he were execute them.
Mosiah 20:17 Now when Gideon had heard these things, he being the king’s captain, he went forth and said unto the king: I pray thee forbear, and do not search this people, and lay not this thing to their charge.
However, Gideon suggested that he not look among his people of the kidnappers.
Mosiah 20:18 For do ye not remember the priests of thy father, whom this people sought to destroy? And are they not in the wilderness? And are not they the ones who have stolen the daughters of the Lamanites?
He reminds Limhi about the missing priests of Noah who were still at large in the wilderness. They might have been the ones who kidnapped the Lamanite girls.
Mosiah 20:19 And now, behold, and tell the king of these things, that he may tell his people that they may be pacified towards us; for behold they are already preparing to come against us; and behold also there are but few of us.
Gideon, tells Limhi to try and convinced the Lamanite king about the priests. The reason being that the Lamanites, even without their king, were preparing to come again against the Nephites but with an even larger army. And this time the Nephites would probably not win this next fight.
Mosiah 20:20 And behold, they come with their numerous hosts; and except the king doth pacify them towards us we must perish.
Gideon, in addition, tells Limhi that they need to get the king of Lamanites convinced of this fact so he can appease the Lamanite army. They will not be able to defeat them this time.