1. There are substances which, if food is covered with them to preserve its heat,¹The Rambam (following the order of the Mishnah, Shabbat, Chapters 3 and 4) continues to explain the possibilities for serving hot food on the Sabbath. In the previous chapter, he spoke about leaving food in an oven or on a range. In this chapter, he describes the possibilities of insulating food with other substances to preserve its heat. Among the other reasons for mentioning these laws in this place is that the activities mentioned must be performed before the commencement of the Sabbath. will raise its temperature and contribute to its being cooked as fire does²The Rambam explains the rationale for this prohibition in the following halachah. - e.g., gefet, manure, salt, lime, sand; nor may we use grape skins, unprocessed wool,³Our translation is based on the Rambam's Commentary on the Mishnah (Shabbat 4:1). Rashi (Shabbat 47b) offers a more inclusive interpretation. or grass⁴The Mishnah (Shabbat 4:1) also mentions hay. The Rambam omits it, probably on the basis of the Jerusalem Talmud, which maintains that this substance will not increase a food's temperature. [for this purpose] when they are damp, even⁵The word "even" has raised many problems, for it implies that these substances will generate more heat when they are moistened from an outside source than when their dampness is a result of their natural moisture. Rashi (Shabbat m49a) states the converse, and this appears to be the opinion of other authorities.

Significantly, in his Commentary on the Mishnah (loc. cit.), the Rambam does not mention the word "even." Similarly, his grandson, Rav Yitzchak HaNagid, writes in a responsum that the inclusion of this word in some manuscripts of the Mishneh Torah was a scribal error. when this is due to their natural moistness. These entities are referred to as substances that increase heat.

There are substances which, if food is covered with them to preserve its heat, will [accomplish that objective alone]. They will not contribute to the cooking process, but will merely prevent [the food] from cooling - e.g., grape skins, unprocessed fabrics, grass, when these are dry, garments, produce,⁶Rashi (loc. cit.) explains that this refers to grains - e.g., kernels of wheat, barley, and the like. Larger produce would not be an effective insulating agent. pigeon feathers, thin chips from the combing of flax, carpenters' sawdust, pelts, and the shearings of wool. These entities are referred to as substances which preserve heat.⁷The Rambam describes the laws pertaining to these substances in Halachot three and four.

2. [The Torah's definition of the Sabbath] laws would allow one to cover food with substances that raise its temperature before nightfall, and thus the food would be covered and its heat preserved on the Sabbath, for it is permitted to leave food cooking on a fire on the Sabbath.

The Sages, however, enacted a decree forbidding covering food with substances that raise its temperature before nightfall,⁸The Shulchan Aruch (Orach Chayim 257:1) states that if one violates this prohibition and covers food with these substances, it is forbidden to partake of the food until Saturday night. The Ramah, however, permits the food to be eaten on the Sabbath if one covered it without knowing of the prohibition. lest the pot boil on the Sabbath and it be necessary to uncover it until its boiling ceases. If one would then cover it again on the Sabbath, one would be covering food with a substance that increases its heat on the Sabbath, and this is forbidden.⁹In his Commentary on the Mishnah (Shabbat 4:1), the Rambam explains that covering the food with these substances does not violate the prohibition against cooking. The prohibition against cooking involves only cooking with fire and heat that results from fire (see Chapter 9, Halachah 2), but not cooking substances with other sources of heat.

The Rabbis, nevertheless, forbade such an act, because it resembles cooking. Furthermore, as a safeguard to insure that this prohibition is not violated, the Sages also forbade covering food before the commencement of the Sabbath with substances that increase its heat.

The Rambam's interpretation is based on Rabbenu Yitzchak Alfasi's version of Shabbat 34a,b. The Ra'avad, Rashi, Tosafot, and many others follow a different version of that passage, which explains that the reason it was forbidden to cover food with these substances is a safeguard against a person covering food with a mixture of ash and coals. (See the following halachah.) This view is accepted by the Shulchan Aruch (Orach Chayim 257:1).

Accordingly, it is permitted to cover food with substances that increase its temperature beyn hash'mashot,¹⁰The time between sunset and the appearance of three stars. The status of this time is a question of doubt: is it considered part of the day or the night? (See Chapter 5, Halachah 4.)

The Maggid Mishneh finds this law one of the more difficult aspects of the Rambam's explanation of this halachah, for there is no other instance where the laws that apply beyn hash'mashot are more lenient than those that apply before sunset. since at that time most pots have already boiled, and they [have cooled, so that] they cease boiling. Since they have already ceased boiling, it is unlikely that they will boil again.

3. Similarly, [the Torah's definition of the Sabbath] laws would allow one to cover food with substances that do not raise its temperature on the Sabbath itself. The Sages, however, enacted a decree forbidding this, lest a person cover food with a mixture of ash and coals that has sparks of fire, and stir the coals.¹¹As mentioned in note 9, the Rambam's interpretation is based on Rabbenu Yitzchak Alfasi's version of Shabbat 34a,b, while other authorities have a different version of that passage. According to those authorities, there is no comparison between these substances, which do not raise the temperature of food, and a mixture of ash and coals. Nevertheless, our Sages forbade covering food with such substances to preserve its temperature on the Sabbath, because they suspected that a person may find the food he desires to cover cold, and put it on the fire to warm.

(It must be noted that according to the Rambam's interpretation, a mixture of ash and coals is considered somewhat analogous to substances that do not raise the temperature of food. The Maggid Mishneh considers this one of the major difficulties with the Rambam's interpretation. Rav Kapach justifies the Rambam's position with a reference to Beitzah 8a, which appears to indicate that such a mixture is not hot.) [As a safeguard against this,¹²In his Commentary on the Mishnah (Shabbat 4:1), the Rambam notes that this explanation appears to contradict one of the principles of Rabbinic law. Our Sages taught (Shabbat 11b), אין גוזרין גזירה לגזירה, "We do not enact a decree to safeguard the observance of a decree that is itself a safeguard." The prohibition against covering the food with a mixture of ash and coals is itself a Rabbinic decree enacted lest one stir the coals. To uphold this decree, the Sages forbade covering food even with substances that will not increase its temperature.

In resolution of this difficulty, the Rambam implies that the principle mentioned above applies only when the two decrees are enacted in different times. When the two decrees are enacted simultaneously, there is no such difficulty (see Beitzah 3a). Since the Rabbis appreciated that the first element of the decree depends on the second, they enacted two safeguards at the same time. the Sages] forbade covering food with any substance¹³In this instance, the Mishnah Berurah 257:8 states that if a person covered a food with these substances on the Sabbath, he may partake of them on the Sabbath. on the Sabbath, even when it will not raise the food's temperature.

4. If one is unsure whether it is before or after nightfall,¹⁴The Rambam is using the wording of the Mishnah (Shabbat 2:7). In his Commentary on the Mishnah, he explains that this refers to the period known as beyn hash'mashot. Since the prohibition against covering food is only a safeguard for a Rabbinic prohibition, it does not apply at this time. one may cover hot food.¹⁵According to the Rambam, this applies regardless of whether one uses a substance that will merely preserve the food's heat or a substance that will increase its heat. According to the other authorities (whose opinion is accepted by the Shulchan Aruch (Orach Chayim 257:1), the leniency applies only to substances that merely preserve heat. Similarly, it is permitted to cover cold food with a substance that will not raise its temperature, to prevent it from becoming colder or to remove its chill.

When hot food that was covered before the Sabbath becomes uncovered¹⁶The use of the passive voice by the Rambam (and by the Mishnah, Shabbat 4:2, his source) should not be interpreted to mean that this leniency is granted only when the food is uncovered accidentally. On the contrary, a person may recover the food even if he intentionally uncovered it, for example, he uncovered it to serve a portion (Shulchan Aruch HaRav 257:8 and the Mishnah Berurah 257:25). on the Sabbath,¹⁷If, however, the food became uncovered before the Sabbath, it is forbidden to cover it again on the Sabbath (Shulchan Aruch HaRav 257:8 and the Mishnah Berurah 257:25). it may be covered again, since one is not increasing its temperature. It is permitted to change the covering of food on the Sabbath - e.g., one may replace clothing with pigeon feathers or replace pigeon feathers with clothing.¹⁸I.e., regardless of whether the second covering is more or less effective than the first, it is permitted to exchange them. Note the Shulchan Aruch (Orach Chayim 257:4), which states that a more effective covering may be placed on food only when it has been thoroughly cooked. If the food is still in need of further cooking, this is forbidden.

5. Should one transfer hot food or water from the vessel [in which it was cooked]¹⁹The vessel in which an object is cooked is referred to as a כלי ראשון, "a primary vessel." This term is relevant to the discussion of the Sabbath laws and the laws of Kashrut. into another vessel, it is permitted to cover the second vessel with a substance that does not raise its temperature on the Sabbath, as one is permitted to cover cold food.²⁰Note Shulchan Aruch HaRav 257:9 and the Mishnah Berurah 257:28, which state that this leniency applies even when the food is still scalding hot. They also state that if the food has cooled totally, it may be covered so that it does not chill even when it has not been removed from the pot in which it was cooked. The prohibition against covering [food] on the Sabbath applies only to hot food in the vessel in which it was cooked. If it was transferred, it is permitted.²¹The transfer of the food to a different pot cools it. Accordingly, the Sages did not consider it necessary to enact a decree as a safeguard to prevent a person from heating the pot in such a circumstance (Shabbat 51a).

6. One may place one metal pot on another metal pot, an earthenware pot on another earthenware pot,²²Our translation is based on the commentary of the Maggid Mishneh. an earthenware pot on a metal pot, and a metal pot on an earthenware pot, and one may seal [either an earthenware pot or a metal pot] closed with dough - one's intent being not that they should be heated more, but that their heat should be preserved.²³The Mishnah Berurah 318:51 extends the scope of this leniency, stating that it applies even when one pot is covered with insulated substances to preserve its heat. The other pot may be placed on the pot and under the substances. The Shulchan Aruch HaRav 318:14, however, forbids such an act, since by doing so, a person will be insulating food on the Sabbath and that is forbidden.

The [Sages] forbade only covering [food] with other substances on the Sabbath. It is, however, permissible to place one vessel on another vessel so that they remain hot.²⁴Note the Shulchan Aruch (loc. cit.:7-8), which questions whether this leniency applies when the lower pot is cooking on a fire or not. One opinion maintains that if the food in the upper pot has been thoroughly cooked, there is no prohibition in placing it on a pot that is cooking on the fire. Since only a Rabbinic prohibition is involved and this does not resemble the normal manner of cooking, there is no reason for stringency. Another opinion maintains that placing food on such a pot is like placing it on the fire itself and is forbidden. The Shulchan Aruch favors the more lenient opinion, as do the later authorities. In contrast, we may not place a vessel containing a cold substance on a hot vessel on the Sabbath, for by doing so one introduces heat to it.²⁵The Shulchan Aruch (loc cit.:6) explains when this prohibition applies: If the food can become hot enough to scald a child's hand, it may not be left on the other vessel. It is permissible, however, to place [cold food on a hot pot] before the Sabbath commences.²⁶See the Beit Yosef (loc. cit. 258) which explains that one is not permitted to leave food that is covered with insulating materials on a fire even if this is done before the Sabbath. It is not considered analogous to covering food with a substance that raises its temperature.²⁷The Shulchan Aruch (loc. cit. 257:8) which differentiates between this law and the other laws mentioned in this chapter, explaining that the prohibition against covering food with substances that insulate it and preserve its temperature applies only when the substances cover the food entirely without leaving a portion of the food exposed.