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Nedarim 13

Matters of substance.

In modern English, we often use the terms vows and oaths interchangeably. But as we’ve seen already in this tractate, these are two very different things. 

On today’s daf, we find a new distinction between oaths and vows. The Gemara tells us that in some ways, vows are more stringent than oaths and in other ways, oaths are more stringent than vows. How so? 

The stricture to vows is that vows take effect with regard to a mitzvah as with regard to optional (activities)which is not the case with regard to oaths. 

The medieval commentator Rashi offers some examples that explain how this difference applies in practice. If one vows not to put on tefillin or not to build a sukkah, the vow takes effect. If the person then does put on tefillin or builds a sukkah, they are in violation of their vow. Of course, if they don’t do those things, they are in violation of Jewish law, since both are mitzvahs. Either way, the vower violates the law.

However, oaths not to fulfill a mitzvah don’t work at all. If one took an oath not to build a sukkah, building one doesn’t violate the oath because the oath never took effect. So when making promises about mitzvot, you have to be more careful when it comes to vows than oaths. 

The Gemara then turns to another distinction between oaths and vows.

And the stricture that applies to oaths is that oaths take effect upon a matter that has substance and a matter that does not have substance, which is not the case with regard to vows.

Again, Rashi offers us an example to make sense of this stringency. What is a matter that doesn’t have substance? Speech. Talking is a kind of action, and it’s a kind of action that can make real legal change (vows, anyone?), but it’s not three dimensional or tangible. It’s not stuff. So if one makes an oath about speech, it takes effect. But vows only apply to tangible things, and so a vow about speech wouldn’t work. 

But this distinction poses a problem because we just read this in a mishnah earlier on today’s daf:

One who says to another: It is konam for my mouth to speak with you, my hand to work with you, my foot to walk with you, it is prohibited. 

Konam is a word for a vow. How could a vow take effect on talking, working, or walking, all of which are actions but not substances? This mishnah seems to be in direct contradiction with the other teaching. 

With some insight from Rav Yehuda, the Gemara resolves this problem by reading the mishnah carefully. After all, the mishnah doesn’t concern vows about actions, but about body parts. 

For my mouth to speak with you, and it does not teach: That which I speak with you. 

Body parts are in themselves tangible, three-dimensional, and made up of a range of substances. So a vow about a body part actually does take effect.

We’re almost two weeks into our study of tractate Nedarim, so it’s not a fresh insight to state that, for the rabbis, words matter. Vows and oaths are not the same thing — they take effect in different circumstances and produce different results. But what today’s daf does offer is a reminder that words matter not only in the making of vows, but in the transmission of rabbinic traditions. With a bit of careful reading, you might discover that what you thought might be a contradiction actually isn’t. And that’s OK — today’s daf itself models the value of reading something a second time more carefully. 

Read all of Nedarim 13 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on November 7th, 2022. If you are interested in receiving the newsletter, sign up here.

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