הנודר מן הבשר מותר בבשר דגים וחגבים:
And one who takes a vow that meat is prohibited to him is permitted to eat the meat of fish and grasshoppers.
גמ׳ הא עוף אסור מדאורייתא כמאן דלא כרבי עקיבא דאי רבי עקיבא האמר חיה ועוף אינו מן התורה
GEMARA: Since the mishna does not distinguish between the meat of animals and that of birds, it may consequently be inferred that the meat of birds cooked in milk is prohibited by Torah law, just like the meat of animals. In accordance with whose opinion is this ruling? It is not in accordance with the opinion of Rabbi Akiva, as, if you say it is in accordance with the opinion of Rabbi Akiva, didn’t he say that the prohibition of the meat of undomesticated animals and birds cooked in milk is not by Torah law?
אימא סיפא הנודר מן הבשר מותר בבשר דגים וחגבים הא עוף אסור אתאן לרבי עקיבא דאמר כל מילי דמימליך עליה שליח בר מיניה הוא
The Gemara continues: But say the latter clause of the mishna: One who takes a vow that meat is forbidden to him is permitted to eat the meat of fish and grasshoppers. It may consequently be inferred that it is prohibited for him to eat birds. If so, here we arrive at the opinion of Rabbi Akiva, who said: Anything about which an agent sent to purchase a given item would inquire, being unsure whether it qualifies as that type of item, is considered its type.
דתניא הנודר מן הירק מותר בדלועין ור"ע אוסר אמרו לו לר"ע והלא אומר אדם לשלוחו קח לנו ירק והוא אומר לא מצאתי אלא דלועין
As it is taught in a mishna (Nedarim 54a): One who takes a vow that vegetables are forbidden to him is permitted to eat gourds, as people do not typically consider gourds a type of vegetable, but Rabbi Akiva deems it prohibited for him to eat gourds. The Rabbis said to Rabbi Akiva: But it is a common occurrence that a person says to his agent: Purchase vegetables for us, and the agent, after failing to find vegetables, returns and says: I found only gourds. This indicates that gourds are not considered vegetables.
אמר להן כן הדבר כלום אומר לא מצאתי אלא קטנית אלא שדלועין בכלל ירק ואין קטנית בכלל ירק רישא רבנן וסיפא ר"ע
Rabbi Akiva said to them: The matter is so, and that proves that my opinion is correct. Does the agent return and say: I found only legumes? Rather, it is evident that gourds are included in the category of vegetables, although they differ from other vegetables, and therefore, the agent explains that he found only gourds, and asks whether he should purchase them. But legumes are not included in the category of vegetables, and that is why an agent would not even ask about them. Therefore, Rabbi Akiva should also hold that one who takes a vow that meat is forbidden to him is prohibited from eating birds. And if so, the first clause of the mishna is in accordance with the opinion of the Rabbis, who disagree with Rabbi Akiva, and the latter clause is in accordance with the opinion of Rabbi Akiva.
אמר רב יוסף רבי היא ונסיב לה אליבא דתנאי בנדרים סבר לה כר"ע בבשר בחלב סבר לה כרבנן
Rav Yosef said: That is not difficult. The entire mishna is in accordance with the opinion of Rabbi Yehuda HaNasi, and he formulates the mishna according to the opinions of different tanna’im. In the latter clause, with regard to vows, he holds in accordance with the opinion of Rabbi Akiva, whereas in the first clause, with regard to meat cooked in milk, he holds in accordance with the opinion of the Rabbis.
רב אשי אמר כולה ר"ע היא והכי קאמר כל הבשר אסור לבשל בחלב מהן מדברי תורה ומהן מדברי סופרים חוץ מבשר דגים וחגבים שאינם לא מדברי תורה ולא מדברי סופרים:
Rav Ashi said a different explanation: The entire mishna is in accordance with the opinion of Rabbi Akiva, as indicated by the latter clause, concerning vows. And as for the first part of the mishna, this is what it is saying: It is prohibited to cook any meat cooked in milk, some types of meat by Torah law, i.e., that of domesticated animals, and some types of meat by rabbinic law, i.e., that of undomesticated animals and birds. This prohibition applies to all types of meat except for the meat of fish and grasshoppers, which are not prohibited, neither by Torah law nor by rabbinic law.
ואסור להעלות [וכו']: אמר רב יוסף שמע מינה בשר עוף בחלב דאורייתא דאי סלקא דעתך דרבנן אכילה גופה גזירה ואנן נגזר העלאה אטו אכילה
§ The mishna teaches further: And it is prohibited to place any meat with cheese on one table. Rav Yosef said: Conclude from this clause that eating the meat of birds cooked in milk is prohibited by Torah law. As, if it enters your mind that the prohibition against eating it applies merely by rabbinic law, this would be because the consumption of the meat of birds cooked in milk is itself a rabbinic decree, lest one come to eat the meat of an animal in milk. And would we decree against placing birds together with cheese on one table due to the possibility of consumption, which is itself a decree? The Sages do not enact one decree to prevent the violation of another decree.
ומנא תימרא דלא גזרינן גזירה לגזירה דתנן חלת חוצה לארץ
The Gemara asks: And from where do you say that we do not issue one rabbinic decree to prevent violation of another rabbinic decree? The source is as we learned in a mishna (Ḥalla 4:8): Ḥalla from outside of Eretz Yisrael, which must be eaten by a priest,