Sanhedrin 67A

סימנא בעלמא.

It is merely a mnemonic. The verse is not relevant to this halakha, and it is cited merely as a sign indicating that just as the halakha of a betrothed young woman pertains to her first act of sex, so too, the halakha of the daughter of a priest who committed adultery pertains to a case where it is her first disqualification from the priesthood.

מתני׳ המסית ⁠– זה הדיוט, והמסית את ההדיוט. אמר: יש יראה במקום פלוני, כך אוכלת, כך שותה, כך מטיבה, כך מריעה.

Mishnah: With regard to the case of an inciter, listed among those liable to be executed by stoning, this is an ordinary person, not a prophet. And it is referring to one who incites an ordinary person and not a multitude of people. What does the inciter do? He says: There is an idol in such and such a place, which eats like this, drinks like this, does good for its worshippers like this, and harms those who do not worship it like this.

כל חייבי מיתות שבתורה, אין מכמינין עליהם, חוץ מזו.

The Mishnah states a principle with regard to the halakha of an inciter: With regard to all of those mentioned in the Torah who are liable to receive the death penalty, if there are no witnesses to their transgressions, the court does not hide witnesses in order to ensnare and punish them, except for this case of an inciter.

אמר לשנים: הן עדיו, ומביאין אותו לבית דין וסוקלין אותו. אמר לאחד: הוא אומר ״יש לי חבירים רוצים בכך״.

The Mishnah elaborates: If the inciter said his words of incitement to two men, they are his witnesses, and he does not need to be warned before the transgression; they bring him to court and stone him. If he said his words of incitement to one man alone, that man’s testimony would not be sufficient to have the inciter executed. Therefore he says to the inciter: I have friends who are interested in this; tell them too. This way there will be more witnesses.