Shevuot 3B

הא דומיא דמראות נגעים קתני ⁠– מה התם כולהו לחיובא, אף הכא נמי כולהו לחיובא!

But the Mishnah teaches these cases similar to the different shades of leprous marks, which indicates that just as there, all 4 of them are shades for which there is liability to bring an offering, so too here, with regard to oaths and the cases of one’s awareness of the defiling of the Temple or its sacrificial foods, all 4 of them are cases for which there is liability to bring an offering.

לעולם רבי ישמעאל; וכי לא מחייב רבי ישמעאל לשעבר ⁠– קרבן; אבל מלקות חיובי מחייב.

The Talmud suggests a different resolution: Actually, the Mishnah expresses the opinion of R' Yishmael. And while R' Yishmael does not deem one liable for oaths pertaining to the past, that is only with regard to liability to bring an offering; but he does deem one liable to be administered lashes.

וכדרבא ⁠– דאמר רבא: בפירוש ריבתה תורה שבועת שקר דומיא דשבועת שוא; מה שוא לשעבר, אף שקר נמי לשעבר.

And this is in accordance with the statement of Rava, as Rava says: The Torah explicitly amplifies the prohibition of taking a false oath to be similar to the prohibition of an oath taken in vain, to teach that one is flogged for its violation. It follows that just as an oath taken in vain pertains to the past and renders one liable to receive lashes, so too, taking a false oath that pertains to the past renders one liable to receive lashes.

בשלמא ״אכלתי״ ו״לא אכלתי״⁠ – כדרבא; ״שלא אוכל״ ואכל נמי ⁠– לאו שיש בו מעשה הוא; אלא ״אוכל״ ולא אכל ⁠– אמאי? לאו שאין בו מעשה הוא!

The Talmud asks: Granted that one who stated: On my oath I ate, but in fact he did not eat, or one who stated: On my oath I did not eat, but in fact he ate, is liable to receive lashes, as this is in accordance with the statement of Rava. And also if one stated: On my oath I will not eat, and he ate in violation of his oath, he is liable to receive lashes, as it is a prohibition that involves an action, and, in general, such prohibitions are punishable by flogging. But if one stated: On my oath I will eat, and in violation of his oath he did not eat, why should he be liable to receive lashes? It is a prohibition that does not involve an action. The generally accepted principle is that one is not liable to receive lashes for violating a prohibition without performing an action.