What has happened to Saul? The targum of ויפל ערם is ונפל ברשן, which רש״י translates based on the Arabic as משוגע, insane. And indeed there is a fine line between prophecy and insanity:
There’s no way to tell from the outside whether someone has actually communicated with G-d or is just hallucinating; להתנבא literally means “to talk to oneself”. All we can judge is whether what the נביא is saying is consistent with the Torah, with being the word of ה׳.
But still, ויפשט גם הוא בגדיו sounds pretty insane. The מפרשים, however, soften it to mean that he removed his royal garments so be part of the בני נבאים:
So it seems that Saul and his messengers were overcome with the sense of נבואה, which kept them from trying to arrest David. Note the use of the word ויתנבא. נבואה reallly has two parts: we think about being a messenger from ה׳ to humanity, but the most important part is the personal connection to הקב״ה. That is the part that can be practiced and learned; whether or not ה׳ decides to use you as a messenger is out of your control. התנבא is the personal part, the “being a spokesman to yourself”:
הנבא is being a spokesman to others:
And there is a principle that a נביא can only reveal his בואה to others if he is commanded to do so; (יומא ד,ב) מנין לאומר לחבירו שהוא
ב״בל יאמר" עד שיאמר לו ”לך אמור“?
שנאמר (ויקרא א:א): וידבר ה׳ אליו מאהל מועד לאמר.
So then what is שמואל doing here? Is רוח אלקים a weapon to destroy שמואל's enemies? On first glance it seems that way, that the messengers and Saul are simply left incapacitated and unable to arrest David, but that is hard to reconcile an earlier episode in Saul’s life:
This is similar to what we saw in David’s prayer that we looked at earlier (תהילים נט:יב) אל תהרגם פן ישכחו עמי. ויתנבאו represents a positive experience, a kind of enlightenment that should change a person forever. And that is what happened to Saul the first time; the expression of הגם שאול בנבאים represents the admiration that the people now had. The tragedy and the irony now is that the second הגם שאול בנבאים shows Saul in his decline; he may be back with the נבאים, and he now leaves David alone, but it will not last. Saul’s paranoia will return in the next perek.
Three Strikes and You’re Out
There is a contrasting story in מלכים, when אחזיה tries to arrest אליהו:
אליהו responds not by bringing the רוח ה׳ on his enemies but by destroying them. שמואל's response is more similar to that of אונקלוס in the gemara: