שצריך לבדקן ואמרי לה מפני שצריך לחסמן
it is necessary to test them to ensure that they do not burst when heated. If they are heated for the first time on a Festival, he will be thereby testing them, which is a prohibited labor. And some say: Because it is necessary to harden them by overheating them the first time to make them fit for use, which is considered preparing a vessel for use and is prohibited on a Festival.
תנן התם דרסה או שטרפה בכותל או שרצצתה בהמה ומפרכסת ושהתה מעת לעת ושחטה כשרה א"ר אלעזר בר ינאי משום ר' אלעזר בן אנטיגנוס צריכה בדיקה
In relation to the above, the Gemara cites the following teaching: We learned in a mishna there: If one trampled fowl with his foot, or threw it against a wall, or if an animal crushed it, and it is twitching but cannot stand; if the animal waited, i.e., remained alive, from the time of the injury until the same time twenty-four hours later, and he subsequently slaughtered it, it is kosher, provided no other defect is found in it that would have caused it to die within twelve months, which would render it a tereifa. Rabbi Elazar bar Yannai said in the name of Rabbi Elazar ben Antigonus: It requires examination after slaughtering, to make sure it does not have a defect.
בעא מיניה ר' ירמיה מרבי זירא מהו לשחטה ביום טוב מי מחזקינן רעותא ביום טוב או לא
In relation to the same issue, Rabbi Yirmeya inquired of Rabbi Zeira: What is the halakha with regard to slaughtering it on a Festival? Do we assume on a Festival that it has a flaw or not? In other words, may one rely on the assumption that a typical chicken has no defect? Or perhaps, since there is concern with regard to this particular bird and it requires examination, one should refrain from slaughtering it lest it turn out to be a tereifa. If so, he will have performed labor for no purpose.
אמר ליה תנינא אין מלבנין את הרעפים לצלות בהן והוינן בה מאי קא עביד ואמר רבה בר בר חנה א"ר יוחנן הכא ברעפים חדשים עסקינן מפני שצריך לבדקן
He said to him in response: We already learned that one may not whiten tiles in order to roast on them. And we discussed it: What does he thereby do? And Rabba bar bar Ḥana said that Rabbi Yoḥanan said: Here we are dealing with new tiles, and the Sages prohibited heating them because one first needs to test them, and they might crack when heated. If they were heated for the first time on a Festival and cracked, it would show that they were unfit for use, in which case heating them would have been an unnecessary labor. This indicates that one may not take a chance on a Festival with regard to something that might be flawed, and therefore a possible tereifa should be similarly prohibited.
אמר ליה אנן מפני שצריך לחסמן מתנינן לה:
He said to him: This is no proof; we learned that the reason for that halakha is because it is necessary to harden them in order to make them into proper vessels. Therefore, there is no connection between making a vessel and conducting an examination. Consequently, there is no reason to prohibit the slaughter of such a chicken on a Festival.
תניא אחד מביא את האור ואחד מביא את העצים ואחד שופת את הקדרה ואחד מביא את המים ואחד נותן בתוכו תבלין ואחד מגיס כולן חייבין והתניא אחרון חייב וכולן פטורין לא קשיא הא דאייתי אור מעיקרא הא דאייתי אור לבסוף
It is taught in a baraita: It is possible for several people to perform a single act of cooking on Shabbat, and all will be liable. How so? One brings the fire, and one brings the wood, and one places the pot on the stove, and one brings the water for the pot, and one puts spices into the food, and one stirs the pot; they are all liable for cooking. The Gemara wonders at this: But wasn’t it taught in a different baraita that the last one is liable and all the rest are exempt? The Gemara responds: This is not difficult. This case, where all are liable, is referring to a situation in which he brought fire at the outset, and therefore each of them performed part of the act of cooking; that case, where only the last one is liable, is referring to a situation in which he brought fire at the end. In that case, none of the earlier people performed any aspect of cooking at all, as the labor of cooking begins only from when fire is brought.
בשלמא כולהו קא עבדי מעשה אלא שופת את הקדרה מאי קא עביד אמר רבי שמעון בן לקיש הכא בקדרה חדשה עסקינן ומשום לבון רעפים נגעו בה:
The Gemara asks: Granted, all of them performed an action that constitutes a prohibited labor, and they are therefore partners in a prohibited act and the desecration of Shabbat. But the one who places the pot on the stove, what prohibited labor has he performed? Rabbi Shimon ben Lakish said: Here we are dealing with a new pot, and due to whitening tiles they applied the same prohibition to it. This means that one is not liable for cooking the food in the pot but for strengthening the pot itself, as is the case with heating tiles.
ת"ר תנור וכירים חדשים הרי הן ככל הכלים הנטלין בחצר אבל אין סכין אותם שמן ואין טשין אותן במטלית ואין מפיגין אותן בצונן כדי לחסמן ואם בשביל לאפות הרי זה מותר:
§ The Sages taught in the Tosefta: New ovens and stoves are similar to all vessels that may be carried in a courtyard on a Festival, as one can place items on them. However, one may not anoint them with oil, nor rub them with a rag, nor cool them with cold liquids to harden them, as all these actions are considered preparing the vessel for use, which may not be done on a Festival. And if one did so in order to bake in the oven on the Festival itself, this is permitted.
תנו רבנן מולגין את הראש ואת הרגלים ומהבהבין אותן באור אבל אין טופלין אותם בחרסית ולא באדמה ולא בסיד ואין גוזזין אותן במספרים
§ The Sages taught in the Tosefta: During a Festival one may scald the head and the feet of a slaughtered animal with hot water in order to remove the hairs from them, and one may singe them in fire for this purpose, but one may not smear them with clay, nor earth, nor lime in order to remove the hairs because this involves great effort, and it appears as though he is processing the skin. And one may not shear those hairs with scissors, as it appears as though he is performing the labor of shearing in an effort to obtain the hairs themselves.
ואין גוזזין את הירק בתספורת שלו אבל מתקנין את הקונדס ואת העכביות ומסיקין ואופין בפורני ומחמין חמין באנטיכי ואין אופין בפורני חדשה שמא תפחת:
Similarly, one may not trim the top of the leaves connected to the vegetable with its special shears, but one may prepare kundas and akaviyot, bitter vegetables that can be eaten only after extensive cooking, although this involves great effort. And one may kindle fire and bake in a large baker’s oven [purnei], and one may heat water in an antikhi, a kind of large urn, but one may not bake in a new baker’s oven lest it break. If the oven cracks when heated because it was not properly made, one will have performed unnecessary work on a Festival.
ת"ר אין נופחין במפוח אבל נופחין בשפופרת ואין מתקנין את השפוד ואין מחדדין אותו ת"ר אין מפצעין את הקנה לצלות בו מליח אבל מפצעין את האגוז במטלית ואין חוששין שמא תקרע:
§ The Sages taught similarly in the Tosefta: One may not blow a fire with bellows, because this is the manner of a weekday activity, but one may blow a fire with a tube, in an unusual manner. And one may not mend a skewer nor sharpen it. The Sages further taught in the Tosefta: One may not break a reed in order to make a kind of skewer upon which to roast salted fish, but one may crack a nut covered with a rag, and there is no concern lest it tear, for even if this occurs, no prohibited labor has been performed.
מתני׳ ועוד אמר רבי אליעזר עומד אדם על המוקצה
MISHNA: And Rabbi Eliezer further stated the following leniency: A person may stand over objects in storage, such as produce that he has for some reason previously set aside from use,