Shevuos Daf 21 חג השבועות דַף 21

Ravin quoted in Rebbe Abahu’s name that Rebbe Yochanan holds that both שבועת שקר and שבועת שוא refer to oaths about the past. One who falsely swears אכלתי ולא אכלתי – “I ate,” or “I did not eat,” where the falsehood is not self-evident, is categorized as שקר. The case of "שוא" – a vain shevuah, is one who was נשבע לשנות את הידוע לאדם – swore contrary to what is known to people (i.e., an obvious falsehood, e.g., that a man is a woman, or that a stone is gold). One who swears “I will eat,” or “I will not eat,” and subsequently violates his shevuah, transgresses the prohibition of "לא יחל דברו" – he shall not defile his word. From the Gemara below, it emerges that all cases of false shevuos, whether about the future or the past, obligate a korban for an inadvertent transgression, including those without malkus because they lack an action (see below). A שבועת שוא does not.

This second version of Rebbe Yochanan was inferred from a statement of Rebbe Abahu. Rebbe Yochanan said a לאו שאין בו מעשה – negative prohibition without an action generally does not incur malkus, with three exceptions, one of them "נשבע". Rebbe Yochanan darshens the words כי לא ינקה ה' – for Hashem will not absolve [one who swears in vain] to teach that only Hashem will not absolve (i.e., punish) him, אבל ב"ד של מטה מלקין אותו ומנקין אותו – but Beis Din below lashes him and thereby absolves him. The double mention of "לשוא" in this passuk teaches that even "שבועת שקר" incurs malkus. Rebbe Abahu asked which case of שבועת שקר Rebbe Yochanan was including for malkus. One who swears he will not eat, and later does eat, transgresses with an action, and obviously incurs malkus. If one swears to eat and does not, Rebbe Yochanan holds he does not incur malkus, since it has no action!? Therefore, the "שבועת שקר" which incurs malkus must be one who swears falsely about the past (similar to a שבועת שוא, which is also about the past).

In the Mishnah on Daf 19b, Rebbe Akiva said that one who swears not to eat and later inadvertently ate a כל שהוא – minimal amount, is liable for a korban עולה ויורד. The Gemara asks, does Rebbe Akiva hold that all eating prohibitions of the Torah are liable for a כל שהוא, like Rebbe Shimon does? Or does he normally hold that a כזית is required, like the Rabbonon, but holds by a shevuah: הואיל ומפרש חייב – since one who specifies to prohibit even minimal consumption is liable for it, סתם נמי חייב – so one who swears without specifying is also liable for a כל שהוא? [This is because a person who swears not to “eat” may not refer to the Torah’s definition of eating (a כזית), but even to minimal eating.] The Gemara quotes a Mishnah in which Rebbe Akiva says that if a nazir soaked his bread in wine, the bread’s volume combines with the wine to constitute a כזית. This proves that Rebbe Akiva ordinarily requires a כזית. An additional proof is brought.