Shevuot 29

Today we continue to explore what it means to take an oath in vain, starting with this mishnah:

Which oath is an oath taken in vain? It is when one takes an oath to deny that which is known 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 — for instance, if one 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.”

Two very different types of false oaths are described in the mishnah. The first is when a person swears to something that is commonly known to be false, for example, that a stone column is really made of pure gold, which would obviously be too soft and too expensive to support a building. The second is when a person attaches their oath to something ludicrous or impossible, such as a flying camel. These are now added to other examples of oaths taken in vain that we have encountered, including swearing not to observe a mitzvah and making two contradictory oaths. 

Nonsensical oaths are likely what Rashi had in mind when he interpreted a shevuat shav, an “oath made in vain,” as an oath that is made idly, or without reason. The medieval Italian commentator Sforno views a shevuat shav as equivalent to perjury, writing that even a person who unnecessarily swears something that is evidently true (e.g., that a rock is a rock), will never be free from the sin of using God’s name for an undignified purpose. 

Back on our daf, we return to the matter of the person who swears to do something on the condition that they did not see a flying camel or a snake as large as the beam of an olive press. In the hands of the talmudic rabbis, the discussion morphs. No longer are we concerned with what qualifies as an oath taken in vain, but with what is truly impossible:

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.

Maybe, says Ravina, “Camel” is actually a nickname for a bird. (Growing up, one of my children’s favorite books was A Porcupine Named Fluffy in which a rhinoceros named Hippo also features.) But no, replies the Gemara: We do not employ personal meanings to signify oaths in court. But the rabbis still wonder if these seemingly impossible things might be real:

And are there no snakes that large? Wasn’t there a certain snake during the years of the reign of King Shapur, one snake that could swallow 13 stables of straw?

Shmuel said: The size of the snake is not the subject of the analogy. The oath is referring to a snake that was flat like the beam of an olive press.

Aren’t they all flat? Snakes’ undersides are flat. This oath is referring to a snake whose back is flat.

Just when the rabbis seem to have found a snake that was in fact so large it rivaled the size of an olive press beam, the rabbis reinterpret the meaning of the oath: It’s about the shape of the snake’s back, not its size.

Exploring whether extra-large snakes really do exist may seem a trivial diversion from the primary subject, but it’s actually critical to our understanding. Once a person utters a binding oath, those words matter. If it was in fact absurd, the one who uttered the oath has likely broken one of the Ten Commandments and taken God’s name in vain. In Hilchot Teshuvah 1:2, Maimonides distinguishes between “light” and “heavy” mitzvot, and places a shevuat shav in the severe column, underscoring that our words not only matter deeply, but that we should make sure not to use them in a manner that diminishes God’s dignity in the process. Sometimes, that determination hinges on whether something that appears absurd at first glance is truly impossible – or not.

See you tomorrow! 

Read all of Shevuot 29 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on May 30, 2025. If you are interested in receiving the newsletter, sign up here.