Swearing to Fulfill a Mitzvah - Rav Ofer Livnat

Publicized in the weekly leaflet Hemdat Yamim - Eretz Hemdah

 
This week in the Daf Hayomi we continue to learn the issue of a person's obligation to fulfill his oaths. In general, a person who mistakenly transgresses an oath must bring a sacrifice, and if he did so purposely, he receives lashes. However, there are a few exceptions to this rule. One of the exceptions is a person who swore to fulfill a Mitzvah. According to the opinion of the Chachamim in the Mishna (27a), a person who swore to fulfill a Mitzvah, and did not do so, is exempt, as one is only liable for oaths dealing with issues that one is not obligated on. However, the Gemara in Nedarim (8a) states that a person may swear to fulfill a Mitzvah, in order to strengthen his commitment to the Mitzvah. This seems difficult, since if the oath has no significance, why is one permitted to swear?

According to the Ba'al Hamaor (Shevuot 12b in the pages of the Rif), the exemption for a person who did not fulfill an oath to perform a Mitzvah, is only regarding the obligation to bring a sacrifice when he transgressed his oath mistakenly. However, if he transgressed purposely, he receives lashes. Therefore, according to his opinion, the oath has significance, and this explains why one is permitted to swear to fulfill a Mitzvah.

However, the Ramban (Milchamot Hashem 13b in the pages of the Rif) claims that the exemption is from lashes as well. According to his opinion, even though the oath is not binding as an oath, since it can serve as a catalyst for fulfilling a Mitzvah, one is permitted to swear in such a fashion, and it is not considered like saying Hashem's name in vain.

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