1) THE DIFFERENCE BETWEEN A SHEVU'AH AND A NEDER
QUESTION: The Gemara cites a Beraisa which says that in one respect, Nedarim (vows) are more severe than Shevu'os (oaths), and in another respect, Shevu'os are more severe than Nedarim.
Nedarim are more severe than Shevu'os because Nedarim take effect on an object of a Mitzvah in the same way they take effect on an ordinary object, while Shevu'os take effect only on acts that are not Mitzvos. RASHI (DH ha'Nedarim) explains that if a person says, "The Sukah I will make is like Konam for me," or "The Lulav that I shake is like a Korban," his Neder takes effect and he may not use the Sukah or the Lulav. In contrast, if he swears, "I will not sit in a Sukah," or "I will not shake a Lulav," the Shevu'ah does not take effect.
Shevu'os are more severe than Nedarim because they take effect even on intangible things, while Nedarim do not take effect on intangible things. For example, if a person swears that he will not sleep, his Shevu'ah takes effect, but if he makes a Neder and says that sleep is forbidden to him, the Neder does not take effect (since sleep is intangible; see Rashi DH Neder).
TOSFOS (DH Mah) cites the Gemara in Nedarim (16b) which asks why a Neder takes effect on a Mitzvah but a Shevu'ah does not. The Gemara answers that the difference between a Neder and a Shevu'ah is that a Neder is an "Isur Cheftza" -- the prohibition takes effect on the object and not on the person. Since the Torah commands the person to sit in a Sukah (and it does not command the Sukah to have a person sit in it), a person's Neder to forbid the Sukah takes effect because it does not directly conflict with the Mitzvah. In contrast, a Shevu'ah is an "Isur Gavra" -- the prohibition takes effect on the person and not on the object. Since the person is obligated to perform the Mitzvah, his Shevu'ah cannot uproot that obligation, and thus it does not take effect.
According to this explanation, however, the words of the Beraisa here are difficult to understand. Why does the Beraisa say that Nedarim are more severe because they take effect on a Mitzvah? A Shevu'ah can also take effect on a Mitzvah, in a case in which the person says, "Sitting in the Sukah is forbidden to me by a Shevu'ah." Such a declaration creates an "Isur Cheftza" because it forbids the the use of the Sukah from the person. Like a Neder, it takes effect because it does not directly conflict with the Mitzvah which applies to the person and not to the object.
ANSWER: TOSFOS (DH Mah) explains that the difference between Nedarim and Shevu'os is that the format of a Neder which takes effect on a Mitzvah (one makes the Cheftza, object, forbidden to him) also takes effect on a non-Mitzvah object. Conversely, when one makes a Neder not in the typical way, but he makes himself forbidden on the Cheftza, the Neder does not takes effect at all, neither on a Mitzvah nor on something which is not a Mitzvah.
In contrast, a Shevu'ah made in the normal manner of a Shevu'ah (one makes himself, the Gavra, forbidden on the Cheftza) does not take effect on a Mitzvah but does take effect on something which is not a Mitzvah.
(See ROSH (#10) who expresses this distinction in a slightly different way. He writes that there is a way to make a Shevu'ah such that it will take effect on a non-Mitzvah matter, but not on a Mitzvah. Therefore, Nedarim are more severe than Shevu'os because an ordinary Neder takes effect on a Mitzvah, while an ordinary Shevu'ah does not necessarily take effect on a Mitzvah.) (D. BLOOM)
2) A SHEVU'AH TO ANNUL A MITZVAH TEMPORARILY
QUESTION: The Gemara (25a) cites a Beraisa which says that in one respect, Nedarim (vows) are more severe than Shevu'os (oaths), and in another respect, Shevu'os are more severe than Nedarim (see previous Insight). Nedarim are more severe than Shevu'os because Nedarim take effect on an object of a Mitzvah in the same way they take effect on an ordinary object, while Shevu'os take effect only on acts that are not Mitzvos. Similarly, the Mishnah later (27a) states that when one makes a Shevu'ah not to perform a Mitzvah, he is exempt from his Shevu'ah because the Shevu'ah cannot take effect on a Mitzvah.
When the Mishnah there says that a Shevu'ah to annul a Mitzvah does not take effect, does it refer to a Shevu'ah in which one swears never to perform the Mitzvah, or does it refer even to a Shevu'ah in which one swears only that he will not perform the Mitzvah now? For example, if a man (of an age at which he is obligated to marry and have children; see Kidushin 20b) swears that he will not get married for a certain number of years, does his Shevu'ah take effect? Perhaps his Shevu'ah takes effect because it does not entirely annul his Mitzvah to have children; he can marry and have children after the period of his Shevu'ah passes. On the other hand, perhaps a person may not make a Shevu'ah to annul a Mitzvah even temporarily, and thus his Shevu'ah does not take effect and he may marry immediately.
ANSWER: RAV ELCHANAN WASSERMAN Hy'd in KOVETZ HE'OROS (#470) cites the TESHUVAS MAHARIT (YD 47), who answers this question based on the words of the Gemara here (25b). The Gemara earlier (25a) records a dispute between Rav and Shmuel in the case of a person who swears falsely that a certain person "threw a stone into the sea." According to Rav he is liable for making a false Shevu'ah, while according to Shmuel he is exempt.
Rav maintains that he is liable because his Shevu'ah can be expressed in both a positive way ("so-and-so threw a stone into the sea") and in a negative way ("so-and-so did not throw a stone into the sea"). Shmuel maintains that he is not liable for such a Shevu'ah because it is not possible to make such a Shevu'ah in the future tense ("so-and-so will throw a stone into the sea"), as he has no control over whether the other person will do the action or not.
Rav argues that there is no requirement that a Shevu'ah be able to be expressed in both the future tense and in the past tense. The only requirement is that it be able to be expressed in either a positive or negative form.
Rav Hamnuna challenges Shmuel's position from a Beraisa. The Beraisa teaches that the oaths, "I did not eat today" and "I did not put on Tefilin today," are valid Shevu'os. The Gemara explains that the oath, "I did not eat today," presents no problem to Shmuel because it is possible to make such a Shevu'ah in the future tense as well ("I will not eat today"). However, the second case of the Beraisa is problematic to Shmuel. How is it possible to swear, "I will not put on Tefilin today"? RASHI (DH Mi Ika) explains that since such a Shevu'ah annuls a Mitzvah, it is invalid.
The Maharit suggests that from the Gemara's assertion that the oath, "I will not put on Tefilin today," is a Shevu'ah to annul a Mitzvah and therefore is invalid, one may infer that the Halachah is that a Shevu'ah to annul a Mitzvah even temporarily is not valid. Had such a Shevu'ah been valid, the Gemara would have said that the oath, "I will not put on Tefilin today," refers to a case in which he had already put on Tefilin, and he swears that he will not put them on again or he will not continue to wear them.
However, the Maharit rejects this argument, because one may argue that the Mitzvah of Tefilin according to the Torah is to wear Tefilin every moment of the day. Therefore, when one says, "I will not put on Tefilin today," his statement is equivalent to nullifying totally today's Mitzvah of Tefilin. Although he still could don Tefilin tomorrow, tomorrow's Mitzvah is a different Mitzvah from today's; a person cannot regain today's Mitzvah of Tefilin by wearing Tefilin tomorrow. Therefore, the oath, "I will not put on Tefilin today," is considered a Shevu'ah to annul a Mitzvah entirely.
(The BI'UR HALACHAH (OC 37:1, DH Mitzvosan) in the name of the PRI MEGADIM concludes that the most preferable way to perform the Mitzvah of Tefilin is by wearing them all day. Nevertheless, one who wears them for one moment during the day fulfills the Mitzvah. One who did not put on Tefilin at all on one day annulled a positive commandment. The SHULCHAN ARUCH (OC 37:1) writes that since a clean body is necessary in order to be able to put on Tefilin, and since one is not allowed to let his attention wander from the Tefilin, the custom today is not to wear Tefilin all day, but one should be careful to wear Tefilin when he says Keri'as Shema and Shemoneh Esreh. See also YOSEF DA'AS.)
In contrast, the Mitzvah to have children requires that during the course of one's lifetime, he must endeavor to give birth to a boy and a girl. Once he has fulfilled this requirement, he is exempt from the Mitzvah. A man who procrastinates performing the Mitzvah to have children does not transgress the Mitzvah; he merely delays it. When he has a boy and a girl later in life, he fulfills the Mitzvah. In contrast, a man must wear Tefilin every day, and if he fails to wear Tefilin one day, he transgresses the Mitzvah.
The Maharit concludes that, in principle, a Shevu'ah is invalid only when it attempts to annul a Mitzvah permanently, but not when it attempts to annul a Mitzvah only temporarily. However, a Shevu'ah not to get married for a certain number of years is considered a Shevu'ah to annul a Mitzvah for a different reason. The RAMBAM (Hilchos Ishus 15:2) writes that a man who passes the age of twenty and does not get married annuls a positive Mitzvah every moment that he does not get married. (D. BLOOM)