GEMARA: Whose opinion is expressed in the mishna? It is apparently the opinion of Rabbi Meir. As, if it is the opinion of Rabbi Yehuda, there is a contradiction, because he does not differentiate whether one takes a vow by saying: An offering, and he does not differentiate whether he takes a vow by saying: This offering. In both cases the vow does not take effect, as he did not use the phrase: Like an offering. The mishna, by contrast, indicates that only a vow that is phrased: An offering that I will not eat of yours, or: This offering that I will eat of yours, does not take effect. If it is phrased: An offering I will eat of yours, it takes effect, as it indicates that his eating will be like an offering.

The Gemara continues its analysis: Say the latter clause of the mishna: If he says: That which I will not eat of yours is not an offering, the food is permitted. The Gemara asks: But didn’t we learn in a mishna (13a) that if one said: That which I will not eat of yours will be for an offering [lekorban], Rabbi Meir forbids the food to him? And Rabbi Abba said that it is rendered as one who says: Your food will be to me for an offering; therefore, I will not eat of yours. The mishna appears to be incompatible with the opinion of Rabbi Meir as well.

The Gemara answers that this is not difficult. That mishna is referring to one who said: For an offering [lekorban], and the vow therefore takes effect. This mishna is referring to one who said: Not for an offering [la lekorban], where he is saying that it should not be an offering, and therefore the vow does not take effect.

MISHNA: If one says: An oath that I will not eat of yours, or: This is an oath that I will eat of yours [she’okhal lekha], or: Not an oath that I will not eat of yours, the food is forbidden.

GEMARA: By inference from the mishna, it may be derived that the statement: This is an oath that I will eat of yours, indicates that I will not eat. And the Gemara raises a contradiction from a mishna (Shevuot 19b): There are two basic types of oaths that are in fact four: An oath that I will eat, and: That I will not eat; an oath that I ate, and: That I did not eat. From the fact that the mishna states: That I will eat, in contradistinction to: That I will not eat; that I ate, and in contradistinction: That I did not eat, it may be derived by inference that an oath that I will eat of yours [she’okhal lekha] indicates: An oath that I will eat. This contradicts our mishna.

Abaye said: The phrase: That I will eat [she’okhal], indicates two expressions, depending on the context in which it is used. How so? If they were importuning [mesarevin] him to eat, and he said: I will eat, I will eat, and he furthermore said: An oath that I will eat [she’okhal], it indicates: That I will eat. However, if he said: I will not eat, I will not eat, and he furthermore said: An oath that I will eat [she’okhal], he is saying: That I will not eat. The oath is intended to reinforce his refusal to eat.

Rav Ashi said that the phrase: That I will eat [she’okhal], cited in the mishna with regard to an oath, is actually saying that he said: That I will not eat [she’i okhal]. The Gemara asks: If so, the prohibition is obvious, as he explicitly took an oath not to eat. What is the purpose of stating this halakha? The Gemara answers: Lest you say that he blundered in properly upholding the wording, i.e., he mispronounced the vow, as his intention was to say: An oath that I will eat [she’okhal], the mishna teaches us that he meant that he will not eat.

Abaye did not state the reason for the ruling of the mishna that was stated by Rav Ashi, as the mishna does not teach the case of: That I will not eat [she’i okhal]. Rather, it teaches the case of that I will eat [she’okhal].

And Rav Ashi turned away [nadei] from the reason that Abaye stated, because he held that the phrase: That I will not eat, also indicates two expressions, depending on the context. For example, if they were importuning him to eat and he said: I will not eat, I will not eat, and subsequently he also said: An oath, then, in this case, whether the wording of the oath was: That I will eat, or: That I will not eat, this expression indicates that he is saying: I will eat. The statement: An oath that I will not eat, should be interpreted rhetorically in this context: Did I take an oath that I will not eat? Certainly I did not, as I will eat.

And there is also a way to interpret the expression: An oath that I will not eat, as indicating its straightforward meaning, i.e., that he is saying: An oath that I will not eat. Therefore, the mishna cannot be interpreted in this manner. Rather, the tanna in tractate Shevuot clearly established a principle: That I will eat, indicates that I will eat, and: That I will not eat, indicates I will not eat. Therefore, the correct version of the mishna must be: That I will not eat [she’i okhal].

MISHNA: This rule, that oaths can render actions, which do not have actual substance, either prohibited or obligatory, is a stringency of oaths vis-à-vis vows, which do not take effect with regard to matters that do not have actual substance. And there is also a stringency of vows vis-à-vis oaths. How so? With regard to one who said: Making a sukka is konam for me, or: Taking a lulav is konam for me, or: Donning phylacteries is konam for me, in the case of vows, the items are rendered forbidden, and he may not perform the mitzva until the vow is dissolved. However, in the case of similar oaths, these items are permitted, as one cannot take an oath to transgress the mitzvot.