and he unwittingly ate figs and set aside an offering for breaking the second oath, and afterward he unwittingly ate grapes alone, he is exempt from liability for breaking the first oath. The grapes are tantamount to a half-measure of his first oath, which was not to eat figs and grapes together, and one is not liable to bring an offering for a half-measure. Here also, where he said: On my oath I will not eat ten, and then said: On my oath I will not eat nine, and he ate nine and set aside an offering for breaking his second oath, and later he ate the tenth, this tenth is tantamount to a half-measure of his first oath, and one is not liable to bring an offering for a half-measure.

MISHNA: Which oath is an oath taken in vain, mentioned in the previous mishna (27b)? It is when one takes an oath to deny that which is known to people to be true, for example, one says about a stone column that it is made of gold, or about a man that he is a woman, or about a woman that she is a man.

Another type of oath taken in vain is when one takes an oath about a matter that is impossible, e.g., if he says: If I did not see a camel flying through the air, or: If I did not see a snake as large as the beam of the olive press.

In the case of one who said to witnesses: Come and testify for me, and they replied: On our oath we will not testify for you, that is an oath taken in vain, because it involves taking an oath to refrain from performing a mitzva. Other examples of this include an oath not to build a sukka, or not to take a lulav, or not to don phylacteries. This type of oath is an oath taken in vain, for which one is liable to receive lashes if he takes the oath intentionally, and for which he is exempt if he takes it unwittingly.

If one said: On my oath I will eat this loaf, and later said: On my oath I will not eat it, the first oath is an oath on an utterance, and the second is an oath taken in vain, as he took an oath to perform an action that would violate his previous oath.

If he ate it, he violated the prohibition against taking an oath in vain. If he did not eat it, he violated the prohibition against breaking an oath on an utterance.

GEMARA: With regard to an oath taken in vain that denies that which is known to people, Ulla says: It is considered known to people when it is a fact that is known to three people.

§ The mishna describes an oath taken in vain where one takes an oath about a matter that is impossible, e.g., where one says: If I did not see a camel flying through the air. The Gemara points out: The tanna of the mishna did not say: On my oath I saw. What is the meaning of: If I did not see? Abaye said: Emend the language of the mishna and teach: On my oath I saw. Rava said: This is part of a larger statement where one says: Let all the produce in the world be prohibited for me if I did not see a camel flying through the air.

With regard to the oath: If I did not see a camel flying through the air, Ravina said to Rav Ashi: Perhaps this man who took this oath saw a great bird and named it for himself: Camel, and when he took the oath, he took the oath according to his own understanding.

And if you would say that we follow his mouth, i.e., the generally accepted meaning of what one says, and we do not follow his understanding, i.e., his own private meaning, but isn’t it taught otherwise in a baraita: When they administer an oath to him in court, the judges say to him: Know that it is not according to your own understanding that we administer this oath to you, but according to our understanding and according to the understanding of the court? What is the reason they say this? Is it not because we say: Perhaps he gave tokens [iskunderei] to his creditor but he calls them for himself: Dinars, so that when he takes the oath, it is according to his own understanding that he takes the oath. Since, in principle, it is possible for him to take an oath according to his private meaning of the words, the court insists that the oath it administers is to be understood according to the words’ generally accepted meaning.

Rav Ashi replies: No, the reason the court admonishes the oath taker is not that the oath can be interpreted according to a private meaning. There, when the court administers an oath, they explain that it is according to their meaning due to deceptions like that of the reed in Rava’s court. In that incident, someone handed his creditor a hollow reed, which he had secretly filled with coins, to hold for him, and proceeded to take an oath that he had given him the money owed to him, whereupon he took back the reed, as the creditor was unaware of its contents. The court admonishes oath takers so that they do not think that they have fulfilled their obligation to take an oath if they engage in such chicanery.

The Gemara suggests: Come and hear a baraita: And so we found that when Moses administered an oath to Israel that they would keep the Torah (see Deuteronomy 29:9–12), he said to them: Know that I am not administering this oath according to your understanding but according to the understanding of the Omnipresent and according to my understanding. And why not let him simply say to them: Keep that which God said? Is it not that he insisted on admonishing them because he was concerned lest they direct the oath in their minds to idolatry, saying that they are taking an oath of loyalty to God but privately intending the oath to be for idolatry? This indicates that the content of an oath can be affected by an oath taker’s private meaning.

The Gemara rejects this: No, Moses explicitly indicated that the oath was according to God’s and his own understanding because idolatry is also referred to with the word: God, as it is written: “You shall not make with Me gods of silver or gods of gold” (Exodus 20:20). Therefore, the generally accepted meaning of the oath is ambiguous.

The Gemara suggests: If private meanings do not affect the content of an oath, let Moses merely say to them: Keep the Torah. The Gemara explains: They could then have taken an oath to keep only one Torah, either the Written or the Oral Torah. The Gemara suggests: And let him say: Keep two Torahs. The Gemara explains: The word: Torah, also has a narrower meaning of a set of halakhic procedures. The Jewish people could then have limited the oath to the law of [torat] the sin-offering or the law of [torat] the guilt-offering. The Gemara suggests: Let Moses administer an oath to keep the entire Torah. The Gemara replies: That could have been understood as referring only to the prohibition of idolatry, as the Master says: The prohibition of idolatry is so severe that with regard to one who denies idol worship, it is as if he affirms the entire Torah.

The Gemara suggests: And let him say to them: Keep the mitzva, i.e., that which you are commanded. The Gemara replies: That could have been understood as referring to only one mitzva. The Gemara suggests: Let him say: Keep mitzvot, i.e., in the plural. The Gemara replies: That could be understood as referring to only two mitzvot. The Gemara suggests: Let him say: All the mitzvot in their entirety. The Gemara replies: That could be understood as referring to the mitzva of ritual fringes, as the Master says: The mitzva of ritual fringes is equivalent to all the other mitzvot.

The Gemara suggests: And let him say to them: Keep 613 mitzvot. The Gemara replies: And according to your reasoning, let him simply say: Take the oath according to my understanding. Why do I need for him to say: According to the understanding of the Omnipresent?