Neder vs. Shevua

Question

Inspired by this answer (and more generally its question):

What is the difference between a Neder (vow) and a Shevua (oath)?

It seems to me that it is generally described as "issur cheftza" (neder) vs "issur gavra" (shevua), with the practical difference being if you make one of them against a mitzva. Can someone explain this in simple terms, preferably with an older source (i.e. Talmud, Rambam, Shulchan Aruch), and not only a modern day citation?

For example: can I make a neder that I will go to work tomorrow, or would that be automatically considered a shevua?

Answer 1

The gemara (Nedarim 2b) says explicitly what the difference is between a neder and a shevuah:

דתנא נדרים דמיתסר חפצא עליה... לאפוקי שבועה דקאסר נפשיה מן חפצא
It taught nedarim where one forbids an object on himself, and excluded shevuot where one forbids one's self from the object.

This distinction follows through to the Rambam (first two halachot in each of hilchot nedarim and shevuot). According to him, shevuot are things you declare about yourself, either as past tense declaratives, or future tense promises. Nedarim are either forbidding the benefit of some object, or declaring it's dedication to something like the Temple treasury thereby also forbidding its benefit to you and obligating you to bring it to its new 'owner'.

If you make a neder to go to work tomorrow, I don't know if it automatically converts into a shevuah, but it certainly is not a neder.

Answer 2

Rambam (Hil. Nedarim 3:7) draws exactly this distinction, based on Nedarim 16b. He says:

ומפני מה נדרים חלים על דברי מצוה. ושבועות אין חלות על דברי מצוה. שהנשבע אוסר עצמו על דבר שנשבע עליו. והנודר אוסר הדבר הנדור על עצמו

Translation from Chabad.org:

Why do vows take effect with regard to mitzvot and oaths do not take effect with regard to mitzvot? Because when a person takes an oath he forbids himself from [partaking of] the entity mentioned in the oath. When, by contrast, one takes a vow, he causes the entity mentioned in the vow to be forbidden to him.

The footnotes there say that this is precisely a gavra vs. cheftza distinction.

In that same chapter, Rambam gives other practical differences between them. For example, matpis (saying "Y is like X") works only for nedarim, because you've declared X to be forbidden and therefore can make Y exactly like it, while that doesn't work for shevuos.

Saying that "I will do something" which is permissible - as in your example of "I will go to work" - is indeed a shevuah. A neder, by definition, is either declaring something to be forbidden to oneself, or taking on an obligation to bring a korban or give tzedakah (Rambam, ibid. 1:1-2 and Matnos Aniyim 8:1).

Answer 3

It seems that if you take a neder to go to work that it would not do anything. The לשון would probably be ’’הרי עלי להלוך לעבודה’’, which makes no sense, because there is no object on which the neder can be חל. However, if you said one of the following: a)הרי עלי שבועה שאלך לעבודה or b) הרי הליכה לעבודה על רגלי קונם or קונם רגלי בהליכה the neder would be חל,for the following reasons: a) it is a נדר בלשון שבועה, which may work (see the frist ר’’ן in נדרים) and b) the issur (קונם) is mentioned specifically on a physical object, i.e. your feet.

Answer 4

vows are on the object and oaths are on the person. I'm pretty sure that is what my rabbi told me.