However, doing so is prohibited. And one may not fasten the pieces together forcefully, and if he fastens them, he is liable to bring a sin-offering for performing a labor prohibited by Torah law. Rabban Shimon ben Gamliel says: If it was loose and could be assembled with ease, it is permitted. Rabbi Abba and Rav Huna bar Ḥiyya relied on this opinion.

The Gemara relates: In the house of Rav Ḥama, Rava’s grandfather, there was a collapsible bed, similar to a weaver’s loom, and they would reassemble it on a Festival. One of the Sages said to Rava: What is your opinion? Do you hold that this is allowed because it is building in an atypical manner? In other words, one is not performing the prohibited labor of building since it is was not performed in the standard manner? Although there is no Torah prohibition, there is, in any case, a rabbinic prohibition. Rava said to him: I hold in accordance with the opinion of Rabban Shimon ben Gamliel who said that if it were loose, it is permitted even ab initio.

MISHNA: One may place a vessel beneath the oil lamp in order to receive burning sparks of oil that fall from the lamp so that they will not cause a fire. And he may not place water into the vessel because he thereby extinguishes the sparks.

GEMARA: The Gemara asks: How is it permitted to position this vessel to receive the sparks, doesn’t he thereby negate the vessel’s preparedness? It is no longer prepared for any use on Shabbat as the sparks accord it set-aside status. The opinion that negating the preparedness of a vessel is prohibited has already been stated. Rav Huna, son of Rav Yehoshua, said: Sparks have no substance. They burn immediately and do not leave behind any trace of oil in the vessel. Therefore, the vessel remains suitable to be moved.

And we also learned in the mishna that one may not place water into the vessel situated beneath the candle because he thereby extinguishes the sparks. The Gemara remarks: Is that to say that we learned an unattributed mishna in accordance with the opinion of Rabbi Yosei, who said that even an action that causes extinguishing indirectly is prohibited? The extinguishing in this case, where water was placed into a vessel, was not accomplished by means of a direct action. His action only caused it to extinguish indirectly.

The Gemara rejects this question in astonishment: And how can you understand it in that manner? Say that Rabbi Yosei said that indirectly causing extinguishing is prohibited on Shabbat; on Shabbat eve did he say this? And if you say that here, too, it is referring to a case where he placed water in the vessel on Shabbat, wasn’t it taught in a baraita: One may place a vessel underneath an oil lamp to receive sparks that fall from the lamp on Shabbat, and, needless to say, placing it there is permitted on Shabbat eve? And one may not put water into the vessel because he will thereby extinguish the spark, even if he placed it there on Shabbat eve, and, needless to say, doing so is prohibited on Shabbat itself. Apparently, the prohibition in the mishna is not at all connected to Rabbi Yosei’s approach. Rather, Rav Ashi said: Even if you say that this mishna is in accordance with the opinion of the Rabbis, it is different here because, in this case, he is not only causing the spark to extinguish. He is hastening its extinguishing, as the sparks are extinguished immediately when they fall into the water (Rabbeinu Ḥananel). In this matter even the Rabbis would prohibit doing so.

When a pot is removed from the fire on Shabbat eve it may be insulated in materials that preserve its heat, but not in materials that increase its heat. Raising the temperature of a pot is tantamount to cooking. The mishnayot that follow list those materials in which such a pot may be insulated on Shabbat eve and those materials in which it may not be insulated.

MISHNA: In what may one insulate a pot of cooked food on Shabbat eve, and in what may one not insulate it? One may neither insulate it in the solid residue of produce that has been pressed free of its oil, nor in manure, nor in salt, nor in lime, nor in sand, whether those materials are moist or whether they are dry. All of these materials spontaneously generate heat when piled for an extended period. Therefore, they add heat to a pot insulated in them.

And one may neither insulate a pot in straw, nor in the residue of grapes that have been pressed for their juice, nor in soft material, e.g., from tattered clothing, nor in grass, when these materials are moist. However, one may insulate a pot in them when they are dry.

GEMARA: A dilemma was raised before the Sages: Did we learn with regard to the residue of olives in the mishna, but the residue of sesame seeds that were pressed for their oil, which produces less heat, may well be used for insulating food on Shabbat eve? Or, perhaps, we learned with regard to the residue of sesame in the mishna, and all the more so insulating food in the residue of olives is prohibited?

Come and hear a resolution to this dilemma from what Rabbi Zeira said in the name of one of the Sages of the school of Rabbi Yannai: With regard to a basket in which one insulated food in a permissible manner, e.g., in dry soft material or the like, it is prohibited to place it upon the residue of olives. Conclude from this that we learned with regard to the residue of olives in our mishna; however, insulating food in the residue of sesame is permitted.

The Gemara rejects this proof: Actually, I can say to you that with regard to actual insulation, the residue of sesame is also prohibited. However, with regard to