היינו קלקולא אמר רבא אמר רב חסדא אמר רב הונא הלכה כרבי ולאסור

this is the corruption that might result from a ruling that renders it prohibited to prepare an eiruv the day before. Therefore, this cannot serve as proof of the conclusive ruling. Rava said that Rav Ḥisda said that Rav Huna said: The halakha is in accordance with the opinion of Rabbi Yehuda HaNasi to prohibit one from preparing either type of eiruv. One may not prepare an eiruv either for courtyards or for boundaries, as the halakha is in accordance with Rabbi Elazar’s version of the opinion of Rabbi Yehuda HaNasi.

תנו רבנן יום טוב שחל להיות בשבת בית שמאי אומרים מתפלל שמנה [ואומר] של שבת בפני עצמה ושל יו"ט בפני עצמה וב"ה אומרים מתפלל שבע מתחיל בשל שבת ומסיים בשל שבת ואומר קדושת היום באמצע רבי אומר אף חותם בה מקדש השבת ישראל והזמנים

§ The Sages taught the following baraita: In the case of a Festival that occurs on Shabbat, Beit Shammai say: One must recite an Amida prayer that includes eight blessings, inserting two additional blessings between the standard opening three and concluding three. As for the two middle blessings, one recites one for Shabbat as an independent blessing and a second for the Festival as an independent blessing. And Beit Hillel say: One must pray an Amida comprising only seven blessings, i.e., the three opening ones, the three concluding ones, and one in between. One begins the middle blessing with Shabbat and concludes it with Shabbat, and he recites a passage referring to the sanctity of the day of the Festival in the middle. Rabbi Yehuda HaNasi says: He even concludes this blessing with mention of both Shabbat and the Festival, saying: Who sanctifies Shabbat, the Jewish people, and the seasons.

ת"ר שבת שחל להיות בר"ח או בחולו של מועד ערבית ושחרית ומנחה מתפלל שבע ואומר מעין המאורע בעבודה ואם לא אמר מחזירין אותו רבי אליעזר אומר בהודאה ובמוספין מתחיל בשל שבת ומסיים בשל שבת ואומר קדושת היום באמצע

The Sages taught the following baraita: In the case of Shabbat that occurs on a New Moon or on one of the intermediate days of a Festival, for the evening, morning, and afternoon prayers, one prays in his usual manner, reciting seven blessings in the Amida, and recites a passage pertaining to the event of the day, i.e.: May there rise and come [ya’aleh veyavo], during the blessing of the Temple service, known as retze; and if he did not recite it, he is required to return to the beginning of the Amida prayer and repeat it. Rabbi Eliezer disagrees and says: This passage is recited during the blessing of thanksgiving, known as modim. And in the additional prayer one begins the fourth blessing, the special blessing for the additional service, with Shabbat, and concludes it with Shabbat, and recites a passage pertaining to the sanctity of the day of the New Moon or the Festival in the middle.

רשב"ג ורבי ישמעאל בנו של רבי יוחנן בן ברוקא אומרים כל מקום שהוזקק לשבע מתחיל בשל שבת ומסיים בשל שבת ואומר קדושת היום באמצע אמר רב הונא אין הלכה כאותו הזוג

Rabban Shimon ben Gamliel and Rabbi Yishmael, son of Rabbi Yoḥanan ben Beroka, disagree and say: Wherever one is required to recite seven blessings, whether in the evening, morning, or afternoon prayers, he begins the fourth blessing with Shabbat and concludes it with Shabbat, and recites a passage referring to the sanctity of the day of the New Moon or the Festival in the middle. Rav Huna said: The halakha is not in accordance with the opinion of that pair of scholars; rather, it is in accordance with the opinion of the first tanna, that in the evening, morning, and afternoon prayers one recites the usual seven blessings and recites a passage pertaining to the event of the day during the blessing of the Temple service.

אמר רב חייא בר אשי אמר רב מניח אדם עירובי תחומין מיום טוב לחברו ומתנה

§ Rav Ḥiyya bar Ashi said that Rav said: If a person forgot to place an eiruv before a Festival occurring on Thursday and Friday in the Diaspora, he may act as follows: He may place an eiruv for the joining of Shabbat boundaries on the first Festival day for the next, i.e., on the first Festival day for the second Festival day kept in the Diaspora, based on a doubt as to which day is the real day of the Festival, and stipulate as follows: If today is in fact the Festival, then tomorrow is a weekday, on which I may walk as far as I wish in all directions; and if today is a weekday and tomorrow is the Festival, I hereby place an eiruv for the joining of Shabbat boundaries for tomorrow. On the following day he makes a similar stipulation with the same eiruv, so that he will have an eiruv for Shabbat.

אמר רבא מניח אדם עירובי תבשילין מיום טוב לחבירו ומתנה

Rava said: A person may place an eiruv for the joining of cooked foods on the first Festival day for the next day and stipulate as follows: If today is a weekday and tomorrow is the Festival, this is my joining of cooked foods, so that I may rely on it to cook tomorrow for Shabbat; and if today is in fact the Festival and tomorrow is a weekday, I may cook tomorrow as on a regular weekday.

מאן דאמר עירובי תחומין כל שכן עירובי תבשילין ומאן דאמר עירובי תבשילין אבל עירובי תחומין לא מאי טעמא דלמקני שביתה בשבתא לא

The Gemara comments: With regard to the one who said this halakha concerning an eiruv for the joining of Shabbat boundaries, all the more so would he permit one to act in this manner concerning an eiruv for the joining of cooked foods. On the other hand, the one who said this halakha with regard to an eiruv for the joining of cooked foods spoke only with regard to the joining of cooked foods; however, as for an eiruv for the joining of Shabbat boundaries, this is not permitted. The Gemara asks: What is the reason for this difference? It is that they did not permit the acquisition of residence on a day of rest, even in a case of uncertainty. However, with regard to an eiruv for the joining of cooked foods, since it is merely symbolic, it is permitted for the sake of the honor of Shabbat.

תנו רבנן אין אופין מיום טוב לחברו באמת אמרו ממלאה אשה כל הקדרה בשר אע"פ שאינה צריכה אלא לחתיכה אחת ממלא נחתום חבית של מים אע"פ שאינו צריך אלא לקיתון אחד אבל לאפות אינו אופה אלא מה שצריך לו

The Sages taught in a baraita: One may not bake bread on one Festival day for the next, i.e., on the first Festival day for the second Festival day kept in the Diaspora. Nevertheless, actually, they said the following established halakha: A woman may fill an entire pot with meat to cook on a Festival, although she requires only one piece for that day, and all the remainder will be for the following day. Similarly, a baker may fill an entire barrel with water in order to heat it up although he requires only a jug of hot water. But with regard to baking, he may bake only that which he requires for that day.

ר' שמעון בן אלעזר אומר ממלאה אשה כל התנור פת מפני שהפת נאפת יפה בזמן שהתנור מלא אמר רבא הלכה כרבי שמעון בן אלעזר

The baraita continues: Rabbi Shimon ben Elazar says: A woman may fill the entire oven with bread, although she does not intend to use it all on that day, because bread bakes well when the oven is full. A full oven has less empty space and is therefore hotter; consequently, filling the oven with bread serves not only to provide bread for the next day but also to improve the bread to be eaten that same day. Rava said: The halakha is in accordance with the opinion of Rabbi Shimon ben Elazar.

איבעיא להו מי שלא הניח עירובי תבשילין הוא נאסר וקמחו נאסר או דלמא הוא נאסר ואין קמחו נאסר

§ A dilemma was raised before the Sages: In the case of one who did not prepare an eiruv for the joining of cooked foods, is he prohibited from cooking for Shabbat and his flour is likewise prohibited, meaning that none of his food may be prepared for Shabbat? Or perhaps only he is prohibited from performing this type of labor, but his flour is not prohibited.

למאי נפקא מינה לאקנויי קמחו לאחרים אי אמרת הוא נאסר וקמחו נאסר צריך לאקנויי קמחו לאחרים ואי אמרת הוא נאסר ואין קמחו נאסר לא צריך לאקנויי קמחו לאחרים מאי

The Gemara asks: What is the practical halakhic difference that emerges from this question? The Gemara explains: There is a difference with respect to whether or not he must transfer ownership of his flour to others. If you say that he is prohibited and his flour is also prohibited, he must transfer his flour to others so that they are able to bake for him if they so desire. But if you say that only he is prohibited but his flour is not prohibited, he need not transfer his flour to others, as they may bake for him even if the flour is not theirs. The Gemara asks: What, then, is the halakha?

תא שמע מי שלא הניח עירובי תבשילין הרי זה לא יאפה ולא יבשל ולא יטמין לא לו ולא לאחרים ולא אחרים אופין ומבשלין לו כיצד הוא עושה מקנה קמחו לאחרים ואופין לו ומבשלין לו ש"מ הוא נאסר וקמחו נאסר ש"מ

The Gemara answers: Come and hear a resolution from the following baraita: One who did not prepare an eiruv for the joining of cooked foods on a Festival eve may neither bake, nor cook, nor insulate food on the Festival for Shabbat that occurs on the following day, neither for himself nor for others, and others may neither bake nor cook for him. What should he do so that he will have food to eat on Shabbat? He must transfer his flour to others, and they may then bake and cook for him. Learn from here, from the fact that the baraita states that he must transfer his flour to others, that he is prohibited and his flour is also prohibited. The Gemara concludes: Indeed, learn from here that this is the case.

איבעיא להו עבר ואפה מאי ת"ש מי שלא הניח עירובי תבשילין כיצד הוא עושה מקנה קמחו לאחרים ואחרים אופין לו ומבשלין לו

Another dilemma was raised before the Sages: In the case of one who transgressed this prohibition and baked on a Festival for Shabbat without having placed an eiruv for the joining of cooked foods on the eve of the Festival, what is the halakha? Is it permitted to partake of his bread and his cooking? The Gemara suggests: Come and hear a resolution to this question from the following baraita: With regard to one who did not prepare an eiruv for the joining of cooked foods, what should he do so that he will have food to eat on Shabbat? He must transfer his flour to others, and they may then bake and cook for him.