Shevuos, Chapter 3, Mishnah 1. In the previous chapters we dealt at length with awareness of tumah, and now at last we enter the discussion of the oaths themselves. Already in the opening mishnah of the tractate we learned "shevuos shtayim she'hen arba" - two forms of oath which are in practice four, as follows:
"shevuah she'ochal" - an oath about the future, that he will eat.
"shelo ochal" - an oath about the future, that he will not eat.
"she'achalti" - an oath about the past, that he already ate.
"shelo achalti" - an oath about the past, that he did not eat.
The measure of eating - the dispute between Rabbi Akiva and the Sages:
The mishnah moves on to discuss how much a person must eat in order to violate his oath: "shevuah shelo ochal, ve'achal kol shehu - chayav, divrei Rabbi Akiva" - if he swore not to eat and then ate any amount at all, he is liable, according to Rabbi Akiva. That is, even though he ate less than a kezayis, which is the standard measure in the Torah, and ate only a small amount, in Rabbi Akiva's view he is liable.
The Sages challenged him on this: "heichan matzinu be'ochel kol shehu shehu chayav?" - where do we find in the Torah that a person who eats something forbidden to him is liable for eating any amount at all? For eating pork the measure is a kezayis; and even on Yom Kippur, where the measure is not a kezayis but rather the amount that settles the mind ('sumei da'atei'), slightly larger than a kezayis - in the end there is a measure there. From where, then, would we derive a measure of any amount at all?
Rabbi Akiva answered them: "ve'heichan matzinu medaber u'meivi korban?" - where do we find a person who becomes liable to bring an offering by virtue of his speech alone? His point is this: at the moment he took the oath he committed no transgression at all - this is not, God forbid, cursing God's name or anything of the sort - and he performed no action at that moment either, and yet by virtue of his speech he comes to be liable for an offering.
It must be, then, that the offering comes for the nullification of the speech - for having performed an act that contradicts what came out of his mouth. And if the liability is for the act that goes against his words, it does not depend at all on the measure of eating, since the essence of the matter is that he acted contrary to what he said. And since one who says he will not eat has in mind and intends not to eat at all, it turns out that even by eating any amount at all he has violated his speech.
Drinking is included in eating:
From the dispute we move to a ruling that all agree upon: "shevuah shelo ochal, ve'achal ve'shasah - eino chayav ela achas" - if he swore not to eat, and he ate and drank, he is liable only once. The reason for this is that drinking is included within eating, and the Gemara even states that one who swore not to eat and then only drank is liable, because drinking is included in eating.
There are two reasons for this:
From logic: when a person says to his friend, "Come and have a taste of something with me," they go in and eat and drink - drinking is automatically included in the language of eating.
From the verse: it says in Devarim "ve'achalta lifnei Hashem Elokecha" - "and you shall eat before Hashem your God," and the verse there lists several items: "ma'aser deganecha" - the second tithe of your grain, "tiroshcha ve'yitzharecha" - and tirosh is wine, that is, a beverage, and even so the verse used the language of eating.
"Shevuah shelo ochal ve'shelo eshteh":
But the Mishnah continues: if he specified both and said "I will not eat and I will not drink," and he then ate and drank - he is liable twice. This requires explanation: after all, we have a principle that "an oath does not take effect upon an oath," meaning that once one oath has taken effect, a second oath cannot take effect on top of it. If so, since he swore that he would not eat, and drinking is included in eating, why should he also be liable for the oath not to drink?
The difference is this: it is true that when a person says simply "an oath that I will not eat," adding nothing further, drinking is included in his oath. But if immediately afterward he went on and swore that he would not drink, he has revealed his intention that in saying "I will not eat" he meant eating alone. It emerges that drinking was never included in the first oath at all, and these are two independent oaths - and therefore, if he ate and drank, he is liable twice.
In summary: in this Mishnah we learned the dispute between Rabbi Akiva and the Sages regarding the quantity of food for which one who swears becomes liable - according to Rabbi Akiva he is liable even for the smallest amount, since the liability comes for having broken his word and not for the quantity eaten. We also learned that drinking is included in eating, both by logic and from the verse "and you shall eat... your wine and your oil," and therefore one who swore that he would not eat, and then ate and drank, is liable only once; whereas one who specifies in his oath that he will also not drink has revealed that his first intention was for eating alone, and for that reason he is liable twice.