Shabbat 18B

מוגמר וגפרית מאי טעמא שרו בית שמאי? התם מנח אארעא. גיגית ונר וקדרה ושפוד מאי טעמא שרו בית שמאי? דמפקר להו אפקורי.

with regard to placing incense and sulfur beneath clothes and silver vessels, respectively, what is the reason Beit Shammai permitted this? The Talmud answers: The case under discussion was not one where the incense was placed in a vessel; rather, there, the incense was placed on the ground, and therefore there was no utensil that was obligated to rest. The Talmud asks further: A tub in which fruit or grains are placed to ferment into beer, and where they stay for an extended period; and a Shabbat lamp; and a pot in which food is being cooked, which they place on the fire while it is still day; and a spit [shapud] on which they placed food to roast while it is still day; what is the reason Beit Shammai permitted placing them on Friday while it is still day even though the prohibited labor continues over time, including on Shabbat? The Talmud answers: These are cases where he declares the utensils ownerless. According to Beit Shammai, the utensils must be declared ownerless while it is still day. Once the utensils are declared ownerless, they no longer belong to a Jew and, consequently, there is no obligation to let them rest.

מאן תנא להא דתנו רבנן: לא תמלא אשה קדרה עססיות ותורמסין ותניח לתוך התנור ערב שבת עם חשכה, ואם נתנן ⁠— למוצאי שבת אסורין בכדי שיעשו. כיוצא בו: לא ימלא נחתום חבית של מים ויניח לתוך התנור ערב שבת עם חשכה, ואם עשה כן ⁠— למוצאי שבת אסורין בכדי שיעשו. לימא בית שמאי היא ולא בית הלל? אפילו תימא בית הלל, גזירה שמא יחתה בגחלים.

The Talmud asks: Based on these conclusions, who is the tanna who taught this Tosefta that A baraita states: A woman may not fill up a pot with pounded wheat and lupines, a type of legume, and place them in the oven to cook on Friday at nightfall. And if she placed them in the oven, not only may they not be eaten on Shabbat itself, but even at the conclusion of Shabbat they are forbidden for a period of time that would be sufficient for them to be prepared, i.e., the time it takes to cook the dish from the beginning, so that he will derive no benefit from a prohibited labor performed on Shabbat. Similarly, the Tosefta said: A baker may not fill a jug of water and place it in the oven on Friday at nightfall to boil the water that is in the jug, and if he did so, even at the conclusion of Shabbat it is forbidden for the period of time that would be sufficient for it to be prepared from the beginning. Let us say that this Tosefta is in accordance with the opinion of Beit Shammai and not in accordance with the opinion of Beit Hillel. The Talmud answers: Even if you say that it is in accordance with the opinion of Beit Hillel, in those cases the rabbis issued a decree due to concern lest the one cooking stoke the coals on Shabbat in order to accelerate the cooking.