פירוש על שבת 4:1

במה טומנין – A person who comes to remove a pot from on to of a double stove on the Eve of the Sabbath and to cover it (i.e., put dishes in the chafing stove to keep them warm) with another thing, and the Sages said that we don’t cover them with something that adds vapor but rather with a thing that preserves the vapor. What is the thing that adds and is prohibited?

Introduction This brief chapter deals with covering up hot food with something that will preserve its heat. The general rule is that the rabbis allowed storage in something that would preserve the heat but not in something that would increase the heat. The reason is that if this were allowed she might store the food in hot coals and then rake the coals to make them hotter. Raking coals is prohibited. When storage is prohibited it is prohibited even if she stores the dish before Shabbat begins.

לא בגפת – the refuse of olives and sesame when gathered together very hot.

In what things may they cover up [food], and in what things may they not cover it up?
They may not cover up [food] in peat, compost, salt, lime, or sand, whether moist or dry; The material in this section adds heat to the dish whether it is moist or dried out.

לחים – they have a lot of vapor, more than when dry.

Nor in straw, grape-skins, rags or grasses, when they are moist; but they may cover up [food] in them when they are dry. The material in this section adds heat if it is still moist but not when it is dry. Hence it is permitted to cover up food with these things when they are dry.

זגין – grape peels, the pomace/shells of grapes, and seeds of grapes.

They may cover up [food] in garments, produce, doves’ wings, carpenters’ sawdust and thoroughly beaten flax. Rabbi Judah forbids [storing] in fine [flax], but permits [it] in coarse [flax]. The material in this section does not add heat and only preserves it. Hence it is permitted to cover up food with these things. Rabbi Judah holds that fine beaten flax adds heat and it is therefore forbidden to cover up food with it.

מוכין – every soft thing is called מוכין/soft, spongy substance – like wool of a vine, detached pieces of soft wool of an animal and the scrapings-off of outworn garments.

בזמן שהן לחין – all of these refer to straw and pomace of grapes and soft-spongy substance and grasses, and moist things that they mentioned [but] moist on account of themselves, not moist on account of liquids that fell upon them after they had dried and moist soft-spongy substances on account of themselves which we find like wool that is close to the tail or wool that is between the thigh of cattle.

נסורת – the fine saw-dust/chips that the carpenters saw/plane from the tree when they saw it with a saw.

נעורת – very thin, when they thoroughly beat the flax (Talmud Shabbat 49a), and they empty it out.

ר"י אוסר בדקה – thin hatchelled flax, but with fine chips/saw-dust he admits that they permit it whether they are thin or thick, but the Halakha is not according to Rabbi Yehuda. For what they (i.e., the Rabbis) prohibited to cover up while it was still day is a something that increases/adds vapor as a decree lest they cover it with hot ashes and he will come to stir the coals when it gets dark, and they forbid to cover it up on the Sabbath with something that does not increase vapor, and even though they do not nullify the decree lest they find his pot that has cooled off and heat it up with fire on the Sabbath. But at twilight [on Friday], it is permissible to cover it up with something that does not increase vapor as we said at the end of the chapter [two of Tractate Shabbat] “במה מדליקין ] – “With what may we kindle the Sabbath lights” for we are not able to make the decree lest he find that his pot has cooled off and he will heat it, for mere pots at twilight are hot. And Maimonides explained that mere pots at twilight are hot, as he explains, that the opinion does not suffer it because of the confusion of textual versions, for the textual versions are opposite each other, for he found in the Gemara that was before him in the chapter במה מדליקין/With what may we kindle the Sabbath candles – that he had the reading – for what reason did they say that we don’t cover it up with a thing that does not increase vapor once it becomes dark, as a decree lest he cover it with hot ashes, and for what reasons did they say that we don’t cover it with something that increases vapor while it is still daylight (on Friday) , decreed lest it becomes hot, and the readings are not such, but rather, for what reason did they say that we don’t cover them with a thing that does not increase vapor once it becomes dark as a decree lest it become hot and we don’t cover it with a thing that adds vapor while it is still daylight, as a decree lest he cover it with hot ashes.