Defining the Prohibition of a Shevu’a Le-Haba (Part 1)
The first mishna of Massekhet Shavuot implies that there are four different varieties of a shevu’at bituy, a personal oath unrelated to judicial litigation. An oath can be articulated about past actions or past inactions. Alternatively, an oath can be declared about future actions or future inactions. Although an oath about the execution of an action is slightly different from one that describes inactivity, the greater difference exists between shavu’ot about the past (le-she'avar) and shavu’ot about the future (le-haba).
The core issur of the shevu’a le-she'avar surrounds the declaration of falsehood (sheker). By describing an event of the past inaccurately, the person has spoken falsely, incorporating it within a formal declaration and associating it with the name of God. Sheker is forbidden at any level, but this formal sheker defiles the presence of God (whose essence does not allow for sheker) and entails a separate violation, possibly even requiring a unique korban (olah ve-yored).
Is a shevu’a le-haba similarly a sheker violation? A false shevu’a le-sha'avar about the past is immediately deemed a false declaration because one has inaccurately presented the past, whereas a shevu’a le-haba may be fulfilled, thereby avoiding the issuing of a false statement. However, once the declaration is violated, the statement is rendered retroactively false and may be similarly problematic.
Alternatively, a shevu’a le-haba may be fundamentally different from a shevu’a le-shava'ar. By taking an oath, a person may be redefining neutral activities as obligatory or forbidden. For example, by taking an oath not to eat bread, the person may be rendering the act of eating bread as forbidden, so that it is now similar to classically forbidden acts, such as consuming neveila. Conversely, by taking a shevu’a to eat bread a person is rendering this classically neutral process into an obligatory act, similar to other obligatory acts, such as consuming matza on the night of Pesach. The halakhic core of shevu’a le-haba may not be whether an oath has been proven false, but conversion of otherwise neutral activities into personal mitzvot or aveirot.
This question clearly influence several debates among the Rishonim, but it appears that several disputes among the Tannaim and Amoraim were also based on this question. Chief among them is the machloket between R. Akiva and the Chakhamim (Shavuot 19b) about a person who swears not to eat food, who then ingests less than a kezayit. Ordinary food prohibitions, such as neveila, are only punishable in quantities of a kezayit. If one’s oath has rendered food as “personally” forbidden, it should only be punishable only in the minimum quantity of a kezayit; this, in fact, is the position of the Chakhamim. By applying a punishment even for lesser quantities, R. Akiva may be assuming that a shevu’a le-haba does not redefine personal acts as forbidden. Rather, after swearing not to eat a certain food, the person must avoid that food so as not to render his previous statements false. Even by eating even lesser quantities, a person has rendered his previous statements false, and thus violated the shevu’a.
A second intriguing machloket surrounds the ability of hatfasa. Rava (Shavuot 20a) maintains that hatfasa only works for a neder, but not a shevu’a. Since a neder redefines the identity of an item, hatfasa offers a shortcut for a subsequent neder; instead of articulating a complete neder, a person can merely associate a new item with a previously neder-banned item and confer it similar status. Since, however, a shevu’a does not redefine the object, but is merely a declared intent (which may or may not prove to be false), hatfasa is not compatible.
Abaye disagrees, extending hatfasa to a shevu’a as well. If a person has sworn not to eat, he can associate a separate shevu’a (for example, not to eat tomorrow) with his previously articulated oath. Perhaps Abaye agrees in principle with the Chakhamim. By swearing, the person has not simply issued words that must be upheld. Instead he has created concrete actions that are now banned or obligated. Theoretically, he can affiliate separate actions with those previously targeted actions through the mechanism of hatfasa.
Perhaps the most striking issue is which Biblical prohibition is violated by issuing a false shevu’a le’haba. This question may influence halakhic questions, such as the terminology of the warning issued. Rav Dimi (Shavuot 20b) claims that shevu’a le-haba violates the prohibition of “lo tishavu be-shmi la-shaker” (Vayikra 19:12), suggesting that – similar to shevu’a le-she'avar – future oaths are a violation of falsehood. By contrast, Ravin (Shavuot 21a) claims that future oaths do not violate the prohibition of sheker, but rather the prohibition of “lo yachel devaro” (Bamidbar 30:3), similar to a neder. A neder clearly creates a new halakhic prohibition surrounding an item. By equating a shevu’a le-haba to a neder and by dismissing the applicability of sheker, Ravin may be asserting that a shevu’a le-haba creates a newly forbidden or obligatory activity – again similar to the logic assumed by the Chakhamim in their debate with Rebbi Akiva about the requisite shiur of kezayit.
Perhaps this question can be further discerned in the machloket between R. Akiva and R. Yishmael about a korban for a violated shevu’a le-she'avar (Shavuot 25a). The Torah describes the korban in the context of a shevu’a le-haba, “Le-hara o le-heitiv” (Vayikra 5:4). Does a korban also apply to a falsely stated oath about the past? R. Akiva compares a future oath to a past oath and therefore extends the korban even to shevu’a le-sh’avar. Perhaps this is consistent with the previous logic attributed to his position that shevu’a le-haba is punishable even for less than kezayit quantities since the issur of a future shevu’a is based on false statements. As a shevu’a le-haba raises a question of sheker, any consumed quantities render the statement sheker. Since shevu’a le-haba is based on statements rendered as sheker, it is structurally similar to a shevu’a le-she'avar. Thus, even though the Torah articulated the korban about a shevu’a le-haba, it can easily be applied to the structurally similar form of shevu’a le-she'avar.
By contrast, R. Yishma’el may have asserted that shevu’a le-haba is fundamentally dissimilar to a shevu’a le-she'avar. The latter is a violation surrounding falsely spoken words, whereas the former renders new banned or obligated actions. In obligating a korban for performing banned actions, the Torah does not necessarily extend that korban to merely speaking falsely. Just because the Torah articulates a korban for shevu’a le-haba does not mean it can be easily extended to shevu’a le-she'avar. The two are completely different experiences and completely dissimilar violations.