- Definition of שבועת שוא – vain oath
The next Mishnah gives examples of a שבועת שוא – vain oath: נשבע לשנות את הידוע לאדם – if one swore to contradict that which is known to people (Ulla explains that it is known to at least three people). For example, he swore about a stone pillar that it is gold, that a man is a woman, or the reverse. Another example: נשבע על דבר שאי אפשר לו – one who swore about something which is impossible, such as: אם לא ראיתי גמל שפורח באויר – “if I did not see a camel flying in the air.” The Mishnah adds that a shevuah not to perform a mitzvah, such as not to take a לולב on Succos or not to wear tefillin, is also a שבועת שוא (since it is impossible to keep). The Gemara asks that swearing “if I did not see a camel flying” is not a meaningful shevuah, and Abaye emends the Mishnah to say that he swore "שראיתי" – that I saw, etc. Rava says he swore to prohibit all produce in the world on himself if he did not see a camel flying (Tosafos explains it is impossible for him to keep this shevuah).
- If a person swears according to his private intent
Ravina asked Rav Ashi why a shevuah about seeing a camel flying in the air is impossible: perhaps he saw a large bird, which he called “camel,” and swore truthfully according to this intent!? If you will say: בתר פומיה אזלינן – we follow his words’ straightforward meaning, ולא אזלינן בתר דעתיה – and do not follow his private intent, this can apparently be disproven: a person swearing in Beis Din is warned that he is not swearing according to his own intent, but according to Beis Din’s intent. This is presumably because he may have given wooden chips to the lender which he called “coins,” and the shevuah would be valid if not for Beis Din’s warning!? The Gemara answers that we are only concerned that he may deceive them with the plain meaning of the words, like the story of the “cane of Rava,” where a borrower filled a hollow cane with coins and handed it to the unsuspecting lender and thus swore truthfully that he had “given” him coins. The Gemara asks a similar question from Moshe telling Klal Yisroel, when they swore to accept the Torah, דעו שלא על דעתכם אני משביע אתכם אלא על דעת המקום ועל דעתי - “Know that I am having you swear not according to your intent, rather according to Hashem’s intent and my intent.” This is presumably so they do not intend their shevuah to refer to an idol they call “god”!? The Gemara ultimately explains that Moshe’s purpose was so they could not annul their shevuah.
- כל העונה אמן אחר שבועה כמוציא שבועה בפיו דמי
The next Mishnah teaches that the laws of שבועת ביטוי apply to all people (including women, disqualified witnesses, etc.), and both inside and outside Beis Din, מפי עצמו – provided the shevuah expressed by his own mouth (not if someone said, “I am משביע you if you ate or not,” and he responded that he did or did not eat). The same is taught regarding a שבועת שוא, except that the former is liable to a korban בשוגג, and the latter is not. The Mishnah concludes: המושבע מפי אחרים חייב – one who is adjured by others is liable, and explains that if one says, “I did not eat today,” or “I did not wear tefillin today,” and someone was משביע him, and he said, "אמן", he is liable. Shmuel said: כל העונה אמן אחר שבועה – anyone who answers “Amen” after a shevuah, כמוציא שבועה בפיו דמי – is like expressing a shevuah with his own mouth, just like a סוטה merely answers "אמן" to the shevuah of the Kohen. This principle is proven from the beginning of the next Perek, and also from our Mishnah, which first says that one must swear himself, and concludes that if another is משביע him he is liable!? The difference must be whether he said “Amen” or not.
