Sotah 31B

עדות אחרונה שאוסרתה איסור עולם ⁠— הרי היא מתקיימת בעד אחד, עדות הראשונה שאין אוסרתה איסור עולם ⁠— אינו דין שתתקיים בעד אחד?

concerning the final testimony of defilement, which forbids her with an irrevocable prohibition, yet it is established by one witness, then with regard to the first testimony, which does not forbid her with an irrevocable prohibition, is it not logical that it should be established with only one witness?

תלמוד לומר: ״כי מצא בה ערות דבר״, ולהלן הוא אומר: ״על פי שני עדים ... יקום דבר״, מה להלן על פי שנים ⁠— אף כאן פי שנים.

Therefore, to counter this derivation, the verse states: “When a man takes a wife, and marries her, and it comes to pass, if she finds no favor in his eyes, because he has found some unseemly matter [davar] in her” (Deuteronomy 24:1), and there, in the laws concerning monetary matters, it states: “At the mouth of two witnesses, or at the mouth of 3 witnesses, should a matter [davar] be established” (Deuteronomy 19:15), teaching that just as the “matter” stated there is established “at the mouth of two witnesses,” so too, here the “matter” of her seclusion must be established “at the mouth of two witnesses.”

עד אומר ״נטמאת״ ועד אומר ״לא נטמאת״, אשה אומרת ״נטמאת״ ואשה אומרת ״לא נטמאת״⁠ — היתה שותה.

The Mishnah discusses the halakha in a case where two single witnesses contradict each other concerning her defilement. If one witness says: She was defiled, and another witness says: She was not defiled, or similarly in the case of those normally disqualified from bearing witness, if one woman says: She was defiled, and another woman says: She was not defiled, she would drink the bitter water of a sota, due to the uncertainty engendered by the contradictory testimonies.

אחד אומר ״נטמאת״ ושנים אומרים ״לא נטמאת״⁠ — היתה שותה. שנים אומרים ״נטמאת״ ואחד אומר ״לא נטמאת״⁠ — לא היתה שותה.

Similarly, if one witness says: She was defiled, and two witnesses say: She was not defiled, she would drink the bitter water. However, if two would say: She was defiled, and one says: She was not defiled, the testimony of the two witnesses is accepted and she would not drink the bitter water, and the husband must divorce her.