Shevuos Daf 20 חג השבועות דַף 20

The third Perek primarily discusses swearing to do or not to do something. Amoraim discuss מתפיס בשבועה – one who attaches to an oath (e.g., he swore not to eat a certain loaf, and then said about another loaf, “This loaf should be like that one”). Abaye says: כמוציא שבועה מפיו דמי – he is like one who expresses a shevuah with his mouth and is bound to it. Rava holds he is not כמוציא שבועה מפיו and is not bound to it. Earlier, Abaye explained a Baraisa to be uncertain about this question. Rava is challenged from a Baraisa teaching that one who makes a neder prohibiting meat and wine to himself “like the day my father died” (on which he had prohibited meat and wine to himself), the neder is effective. This proves that מתפיס בנדר נדר – one who attaches to a neder is itself a new neder and should prove that מתפיס בשבועה is also considered a שבועה!? The Gemara answers that the Baraisa is not discussing מתפיס בנדר, which is where he merely said, “This day should be like that one.” Rather, it is discussing a primary neder, where he explicitly prohibited meat and wine “like the day my father died,” and teaching it must be hinged on a "דבר הנדור" – something prohibited by a neder.

Rav Dimi quotes Rebbe Yochanan defining which prohibition applies to which type of shevuah transgression: אוכל ולא אוכל – if one swears, “I will eat,” or “I will not eat,” and then violates his shevuah, שקר – it is categorized as a false shevuah (made false by his transgression), and prohibited by the passuk: לא תשבעו בשמי לשקר – you shall not swear falsely by My Name. אכלתי ולא אכלתי – If he swears, “I ate,” or “I did not eat,” swearing falsely about a past event, שוא – it is categorized as a vain shevuah (i.e., immediately false), and prohibited by the passuk: לא תשא את שם ה' אלקיך לשוא – you shall not bear Hashem’s Name in vain. קונמות, i.e., nedarim (violations), are prohibited by "לא יחל דברו" – he shall not defile his word. [Knowing the particular prohibition is essential for giving the correct התראה to a transgressor.] This is challenged from a Baraisa stating: שוא ושקר אחד הן – a vain shevuah and a false shevuah are one, which presumably means they are both about the past!? The Gemara ultimately answers that they are “one” only in that either violation incurs malkus (alternatively, that either inadvertent violation obligates a korban).

Earlier, the Gemara suggested that the Baraisa’s equating שבועת שקר and שבועת שוא was not that both are about the past, but that they were both spoken by Hashem simultaneously, similar to that which a Baraisa teaches: זכור ושמור בדיבור אחד נאמרו – the commandments to “Remember” and “Guard” Shabbos were said by Hashem with a single utterance (i.e., simultaneously, based on the text discrepancy between the first and second sets of עשרת הדברות), מה שאין יכול הפה לדבר – which the human mouth is incapable of saying, ומה שאין האוזן יכול לשמוע – and the human ear is incapable of hearing. However, this interpretation is rejected. Regarding זכור and שמור, the Baraisas says they were spoken together to teach: נשים חייבות בקידוש היום דבר תורה – women are Biblically obligated in the mitzvah of kiddush for the day of Shabbos, because the simultaneous speaking of זכור and שמור teaches כל שישנו בשמירה ישנו בזכירה – whoever is subject to “guarding” (i.e., the prohibited מלאכות) is subject to “remembering” (i.e., kiddush). Since women are obligated in the מלאכות of Shabbos, they are likewise obligated in kiddush. Comparing שבועת שקר and שבועת שוא, however, would not teach anything.