Shiur #18: A Shevu’a

  • Rav Moshe Taragin




In our previous shiur, we assessed the reason that a shevu’a cannot be formed about halakhic activities or mitzvot. One approach suggests that a shevu’a - by definition can only impact voluntary activities. Alternatively a shevu’a may fail at the level of "execution" – when faced with a dilemma whether to break a shevu’a by performing a mitzva or omit the mitzva in order to fulfill the shevu’a, a person must prioritize the mitzva. This shiur will explore secondary applications of this question.

Would a shevu’a apply to a mitzva if it doesn’t create an insoluble clash? In one of his teshuvot (4:91), the Rashba examines a shevu’a not to perform a mitzva until a particular time; once the time has elapsed, the shevu’a expires and the mitzva can be performed. The Rashba claims that in this instance, the shevu’a would obtain since it does not eliminate the possibility of mitzva performance. Presumably, the Rashba believed that a mitzva is not “outside the domain” of a shevu’a; if it were, the time delay and the absence of an ABSOLUTE clash would not matter. A shevu’a cannot address halakhic activites! Evidently, execution of the mitzva overrides fulfillment of the shevu’a in a typical shevu’a to absolutely suspend a mitzva. Since this specific scenario allows both mitzva performance and shevu’a obligation, the shevu’a isn’t cancelled.

What about an inverse situation, in which the shevu’a doesn’t pertain to a mitzva per se but nonetheless creates a clash between mitzva performance and shevu’a commitment? The Birchat Shmuel (Nedarim 12:2) presents this situation regarding someone who takes an oath to perform an activity that would indirectly inhibit mitzva performance. An example would be an oath to work all day long, thereby preventing tefillin performance. The Birchat Shmuel asserts that the oath would fail, even though it wasn’t articulated about a mitzva activity. Presumably, the clash between the oath and mitzva opportunity scuttles the oath. Once again, had the failure of shevu’a al ha-mitzva been more fundamental regarding the domain of a shevu’a, this oath articulated about a non-halakhic act might have been valid.

A related question surrounds an oath to cancel a mitzva that is articulated as a shevuat kollel (loosely translated as a broad spectrum oath). The Yerushalmi (Shavuot 3:4) appears to validate an oath not to eat matza, even though it cancels the mitzva of matza on Pesach. The oath in this case addressed year-round consumption of matza as well, which isn’t a mitzva and which is clearly regulated by the shevu’a. As a more broad-spectrum shevu’a kollel, it would also apply to halakhic matza eating. Some (Ba'al Ha-Ma'or) claim that this exception is rejected by the Bavli, thereby yielding a machloket as to whether a broad-spectrum shevu’a or kollel can cancel a mitzva. Simply understood, this case resembles the issue of the Birchat Shmuel in as much as the topic of the shevu’a is not a halakhic act, while a clash between mitzva performance and shevu’a fulfillment is inevitable. Evidently, the Yerushalmi assumed that typically shevu’a cannot apply to a halakhic activity; in the case of year round matza consumption, the shevu’a isn’t primarily addressing a halakhic activity. By contrast, the Bavli (according to the Ba'al Ha-Ma'or) may interpret the non-application of shevu’a to mitzva as based upon the practical clash. Since this broad-spectrum shevu’a and mitzva clash on Pesach, the shevu’a is cancelled.

Interestingly, this position of the Ba'al HaMa'or’s would be consistent with his previous statement that a shevu’a to reinforce a mitzva is valid. Since the primary issue – at least according to his interpretation of the Bavli – is the clash between shevu’a and mitzva, it does not apply when the shevu’a bolsters the execution of a mitzva. In fact, shevu’a kollel would be the logical inverse of a shevu’a to uphold a mitzva. The former case presents a clash even though it does not primarily address a halakhic activity. The latter case of a shevu’a to uphold a mitzva addresses a halakhic act, but it does not create a clash.


However, the issue of shevu’a kollel is not as absolute as the previous logic suggests. Indeed, the Ba'al Ha-Ma'or believes that the Bavli absolutely rejects a shevu’a kollel to cancel a mitzva. Many Rishonim offer more intermediate positions, claiming that although the Yerushalmi does endorse shevu’a kollel to cancel a mitzva to eat matza, the Bavli rejects shevu’a kollel in certain situations while endorsing it in others. In particular, the R'i (cited by Tosafot, Shavuot 25a) differentiates between cancelling a mitzvat asei through shevuat kollel (such as swearing never to eat matza, thereby attempting to suspend matza consumption on Pesach night) and obligating an aveira (such as swearing to eat both permissible meats as well as forbidden meats). According to the Bavli, a shevu’a kollel to passively suspend matza eating will obtain, whereas a shevu’a kollel to actively perform an aveira will not.


This position presents a complex but extremely important logical construct. Two conditions are necessary in order for a shevu’a to cancel a mitzva to obtain: the shevu’a must be "kollel" – asserting non-consumption of matza year round – and it must cancel a mitzva through passivity (as opposed to obligating eating neveila, even if asserted through kollel). If two conditions are necessary to validate a shevu’a to cancel a mitzva, it is likely that there are two disqualifications for shevu’a levatel mitzva. Perhaps a halakhic activity (such as eating matza or eating neveila) is beyond the domain of shevu’a and a shevu’a that practically clashes with a mitzva/aveira is overruled. A shevu’a kollel “solves” the issue of domain, since it does not primarily address a halakhic activity. However, a shevu’a kollel to eat neveila still entails an extreme clash between the shevu’a, which obligates ingestion of neveila, and the averia, which demands avoidance. This shevu’a fails at the level of compliance. In contrast, a standard shevu’a not to eat matza on Pesach night (as opposed to shevu’at kollel) may not provide an extreme clash, since the shevu’a merely mandates passivity, rather than active violation of an aveira. However, this shevu’a fails anyway, since it directly addresses a halakhic activity of eating matza on the night of Pesach. Hence, only a shevu’a kollel about passive non-performance of a mitzva applies, since neither of the two classic concerns are relevant. It does not create a clash, since it mandates passive non-compliance, and it addresses a general activity and does not specifically target a halakhic act.


This logical construct appears often in Talmudic conversations and should typically be analyzed in the aforementioned fashion.  Whenever two conditions are necessary for the successful application of a halakha it is likely that the halakha faces two different deterrents. If only one of the conditions exist, one deterrent is nullified but the halakha still fails based on the other deterrent. The presence of two conditions nullifies two deterrents and the halakha can be successfully implemented.