Shiur #15: Retention, and Shehiya
LAWS OF SHABBAT: COOKING
By Rav Yosef Zvi Rimon
Dedicated in memory of Joseph Y. Nadler zl, Yosef ben Yechezkel Tzvi
Shiur #15: Chapter 17 Retention, and Shehiya
May one leave uncooked dishes on the fire on Friday?
Is it permissible to put dishes on a gas burner if it is covered by a blech (a plate of tin)?
Which dishes can one put on an electric hot plate before Shabbat? May one put cold soup on it if it will not heat up before Shabbat commences?
Aside from the actions that the Torah forbids because of bishul, the Sages have banned a number of actions related to heating the food. Some of the decrees emerge from the concern that in the context of the desire to maintain the heat of the food, one may come to rake the coals, i.e., stirring the coals in order to intensify the flames; by this, one will violate the Torah prohibition of mavir, kindling. In other cases, the Sages forbid (according to certain Rishonim) actions that appear like bishul (mechzi ke-mevashel).
We may speak of three essential rabbinical decrees:
1) Shehiya (retention): Putting a dish on the fire before Shabbat, so that it will continue cooking or being heated on Shabbat.
2) Hachazara (replacement): Putting a cooked dish back on the fire. This includes putting it there initially (netina).
3) Hatmana (insulation): Insulating or covering food. There are a number of types of wrapping, and there is a distinction between doing so before Shabbat or during Shabbat.
In the coming shiurim, we will examine each of these decrees, their reasons and their parameters.
The mishna (17b-18a) cites a dispute between Beit Shammai and Beit Hillel concerning the application of the labors of Shabbat to inanimate possessions. The former believes that just as Jews must observe Shabbat, so too must their property; the latter believes that Shabbat is not applicable to vessels, but only to people and their livestock. According to this, Beit Shammai should forbid putting food on a stove before Shabbat so that it will cook on Shabbat, because the appliance is performing labor on Shabbat, while Beit Hillel should not view it as a biblical prohibition (even if we are talking about something uncooked), and this is how we rule halakhically.
However, the Gemara (18b) does indicate that Beit Hillel agrees that there is a rabbinical prohibition involved:
Our rabbis taught: A woman must not fill a pot with pounded wheat and lupines and put it in the oven on Friday, shortly before nightfall
Shall we say that this agrees with Beit Shammai, but not Beit Hillel? In fact, you may even say that it is accepted by Beit Hillel: it is a preventive measure, lest one rake the coals.
Thus, Beit Hillel concedes that there is a rabbinic prohibition to put a pot on the flame before Shabbat so that the dish will cook on Shabbat itself. The reason for this prohibition is that we are considered lest a person will be eager to accelerate the cooking and will come to rake the coals, a violation of the melakha of kindling.
This prohibition, called shehiya, is what appears in the Mishna (36b), and from the context there we may derive when the Sages forbid this and when they allow it:
If a stove is heated with stubble or twigs, a dish (tavshil) may be put thereon; with peat or wood, one may not put it thereon, unless one sweeps or sprinkles ashes upon it.
Raking the Coals
Stubble and twigs are fuels that cannot be turned up; instead of becoming coals, they are burnt up. On the other hand peat (from olives) and wood are fuels that become coals, and they can be stoked and raked in order to intensify the fire. The Sages forbid putting a pot on a coal-fueled stove, since stoking is an issue, but a stubble- or twig-fueled stove is not problematic, since there are no coals to stoke.
Sweeping and Sprinkling
The Mishna does offer a solution for a coal-fueled stove: if the coals are swept to the side, or if ashes are poured on them (making the stove, respectively, gerufa or ketuma), a pot may be put on the stove, since stoking the coals is no longer an issue. Below, we will analyze what makes a stove gerufa or ketuma, particularly for our modern ranges and hot plates.
Shehiya of Minimally Cooked Food
The Gemara (20a) cites the view of Chananya:
Chananya says: Whatever is like the food of ben Derusai may be kept on the stove, though it is not swept or sprinkled with ashes.
As we saw in our first shiur, the level of minimal cooking observed by the highwayman ben Derusai is a matter of dispute: the Rambam (9:5) quantifies it as one-half cooked, while Rashi (ad loc. s.v. Ben) quantifies it as one-third cooked. Chananya believes, in any case, that when food reaches the level of Ben Derusai, the prohibition of shehiya does not apply. The reason for this that when the food is already edible (even if only minimally so), the person is not so eager to accelerate the cooking, so there is no concern that one will stoke the coals.
However, the Gemara (36b) raises the possibility that the Sages argue with Chananya, and according to them, one should not leave on an unswept, unsprinkled stove any food that would benefit from further cooking, because for every food such as this, we must be concerned that someone will stoke the coals. According to them, one is allowed to leave on such a stove only a dish that is fully cooked to the extent that any further cooking will be detrimental (mitztamek ve-ra lo).
Following the Gemara, the Rishonim argue as to the halakhic ruling: Rashi (37b, s.v. Ve-Rav Sheshet) and Tosafot (37b, s.v. Amar Rav Sheshet) rule in accordance with Chananyas view: shehiya is not forbidden for a food that is maakhal ben Derusai, while the Rif (16a, Rif) and Rambam (3:4) rule that the halakha does not follow Chananya, and only a fully cooked dish may be left on an unswept, unsprinkled stove.
Halakhically, the Shulchan Arukh (253:1) cites both views but does not express a preference; the Rema explicitly endorses the lenient view of Chananya.
One may not put a dish on it during daytime to leave it there, unless it is fully cooked and further cooking is detrimental
However, if it is only partially cooked, or if it is fully cooked and further cooking is beneficial, we are concerned lest one rake. One cannot leave it there unless one sweeps, removing all of the coals from it, or sprinkles, covering the coals with ashes to reduce their heat
There are those who say that if it is cooked like maakhal ben Derusai, or if it is fully cooked and further cooking is beneficial, one may leave it on the stove even if it is neither swept nor sprinkled
Gloss [of the Rema]: The custom is to be lenient, following the latter view.
The halakhic authorities differ as to the view of the Shulchan Arukh; many believe that he supports the lenient view as well (Minchat Kohen, II, 4; Kaf Ha-chayim 253:23).
According to this, it is permissible (for Ashkenazim, and most Sefardim agree) to put any food that has reached the level of maakhal ben Derusai even on an open fire.
We should note that when keeping a food that is not fully cooked on the fire, one must avoid accelerating the bishul in any way on Shabbat. The Rishonim argue whether the prohibition of bishul is applicable to a food that has reached maakhal ben Derusai (see note 8); however, the Shulchan Arukh (318:4) is stringent about this and writes that a prohibition of cooking is applicable to any dish that is not fully cooked. Therefore, when one puts on the fire a food that is not fully cooked, one should be careful that no one in the house will remove the lid and replace it, since covering the pot is forbidden because of bishul, as we saw in a previous shiur. Therefore one should be strict and not move the pot to a hotter place on the hot plate and the like.
May one put cooked soup that is cold on the fire before Shabbat? As we have already seen, concerning this soup, there is a prohibition of bishul because it has cooled. Apparently, for the same reason, one should leave the soup on the fire before Shabbat, because it is considered uncooked. However, the Chazon Ish (37:27) believes that one may be lenient about this. In his view, it is true that halakhically the soup is considered uncooked, and therefore there is a biblical prohibition of bishul, but when it comes to shehiya, the question is pragmatic: how much motivation is there to stoke the coals? Since realistically, the soup has already been cooked, the motivation to stoke is low (even though the soup is cold) and therefore one may ab initio leave the soup on the fire before Shabbat.
To summarize, one may leave food on an open flame before Shabbat, if it can be eaten in extreme situations (maakhal ben Derusai). In this case, even if the food is now cold, one may leave it, even if it is a liquid. However, generally we are accustomed to use an electric hot plate or a blech (tin cover) for the range, and this allows us to reheat foods over the course of Shabbat, as we shall see below and in future shiurim. Nevertheless, sometimes a person may be staying in a place where there is some difficulty in the matter, and sometimes there are electric heating vessels that do not have the status of gerufa or ketuma (a hot-water urn and the like). Therefore, one must know the letter of the law: one may be lenient about the shehiya of those items we have mentioned even when there is an open, uncovered flame.
SHEHIYA OF TOTALLY UNCOOKED FOOD
The Gemara (18b) explains that totally uncooked food may be left before Shabbat on the fire, even if it is not covered.
A raw dish may be put in an oven before Shabbat shortly before nightfall. What is the reason? Since it will not be fit for the evening, he puts it out of his mind and will not come to rake the coals. Again, if it is cooked, all is well. If it is partly cooked, one is forbidden to do so. Yet if a raw bone is thrown into it, one is permitted to do so.
According to this passage, raking the coals is not an issue because the dish will not be ready for the evening meal even with it, while it will be ready for the morning meal even without it. Therefore, the person puts it out of his mind.
Thus, we learn that a dish that has begun to cook but has not yet reached the level of maakhal ben Derusai is more problematic than a completely raw dish, because with the former there is a reason to be concerned that one may rake the coals in order to make it ready for supper. This concern does not apply to raw food, which in any case will not be ready for supper. The Shulchan Arukh (253:1) rules that shehiya is not forbidden for a raw dish.
Addition of a Raw Food
The passage concludes by noting that a raw bone saves the whole dish; since this one element is totally uncooked, one does not think of it, so shehiya is not forbidden in this case.
According to the view of the Rambam (Commentary to the Mishna 3:1), this applies to any raw food:
If the dish is partly cooked, but one puts in at the time of insulation something raw, e.g. meat or vegetables, it is permitted to leave it on the coals, because one puts it out of his mind.
Rav Yosef Karo (Beit Yosef, 253, s.v. U-ma she-katav ve-im natan) understands that although the vegetables cook quickly and will be ready for the evening meal, the very fact that one puts raw items in the dish shows that one is diverting his attention from it, and therefore leaving it on the stove is allowed.
However, the Rambam (3:8) writes that one must put in a raw limb. This is what other Rishonim indicate, that only raw meat serves this purpose, since it will not be ready by the time of the evening meal, and no other raw foods, which will be ready for the next meal. This is what the Mishna Berura (253:9) writes:
This only applies to raw meat, which will not cook by the evening meal, but for vegetables and other things that are easily cooked, it does not help even if they are raw.
Must it be raw meat, or may one use any food that will not cook by that evening? For example, we now have a crockpot (electric slow-cooker), in which many dishes of legumes or vegetables will not be ready for supper. Is one allowed to leave in it raw food, even without a blech and with the knobs uncovered (see below)?
The Chazon Ish (36:3) deals with this question:
As for a cauldron on the oven filled with water before Shabbat and lighting a low flame under it, which burns all through the night, and when one wakes in the morning, it appears that one may be lenient even though water is forbidden even when it is raw because it cooks quickly, so that rawness is not a reason to allow it nevertheless, if one adds so much water that making it boil is harder than cooking meat, it appears that a great deal of water is like tossing a raw bone into it.
The important issue is whether this will be ready for the night. If the vessel contains so much water that this will not happen, it may be left on an unswept, unsprinkled stove.
According to this, even if the food is something that would normally cook quickly, if it has been put on the fire in such a way that it is clear that even raising the flame will not make it ready for the night of Shabbat (a small flame, crockpot, etc.), one may be allowed to leave it on an unswept, unsprinkled stove. Conversely, one may not leave a pot on a fire with raw meat if turning the flame up could lead to the meat being ready for the evening meal (see Beiur Halakha 253:1, s.v. Mesiach).
However, we must note that this is applicable only to a food that is not cooked at all. A food that has started cooking cannot be left on an unswept, unsprinkled stove, even if it is clear to us that it will not be ready by the time one sits down for supper.
What is the beginning of cooking for this issue? The Mishna Berura (253:11) explains that bishul starts at the moment that the dish is warm, while the time in which it becomes hot is not considered part of the bishul process. The Chazon Ish (37:22) explains that the reference is to the heat of yad soledet bo. According to him, for this issue we do not consider the time at which one accepts Shabbat, but rather the time at which Shabbat commences of its own accord, i.e., sunset (this is implied by the Mishna Berura, op. cit. 10). According to this view, one may leave uncooked food only if we are certain that by sunset it will not reach the heat of yad soledet bo (e.g., putting it on the fire when it is cold or frozen, right before Shabbat begins).
Replacing the Lid
One should note that if one puts a raw food on the fire (abiding by the above-mentioned conditions), one must be careful not to remove and replace the lid, because this is an acceleration of the cooking, which is biblically forbidden. If there is a concern that one of the family members will pick up the lid and replace it, one should always eschew this allowance, using it only this in cases of unique pressure, and even then, one must mark the pot and verify that no one will lift up the lid before it is cooked.
To summarize, one may put food before Shabbat even on an open fire, even a dish that is totally uncooked, if it will not be ready for the evening meal even were one to turn up the fire. One should put the dish up just before candle lighting, and one should be sure that it will not reach a scalding temperature by sunset. On a covered fire or a hot plate, one is certainly allowed to place an uncooked dish (we will deal with a partially-cooked dish in a future shiur).
In any case, one must be careful and warn the people of the household not to lift the lid until the morning (or until a point when it will certainly be ready), so that they will not cover the pot and come to a question of the prohibition of bishul.
Translated by Rav Yoseif Bloch
 The mishna and Gemara do not explicitly mention that the reason for the prohibition is lest one come to stoke the coals; however, almost all Rishonim explain the reason of the prohibition in this way, according to the Gemara (18b), as we saw above (Tosafot 36b, s.v. Lo yitten; Rambam 3:3, 17; Rashba 36b, s.v. Ad she-yigrof; Rosh 3:1). This is how the Shulchan Arukh explains (253:1) the motivation. However, Rashi on the mishna (s.v. Aval) raises another reason, mechzi ke-mevashel, which requires in-depth analysis beyond the scope of this forum.
 The Sages do not say this explicitly, but we may conclude this from the words of the above-mentioned source. The mishna simply states that one should not put a tavshil on a stove fueled with peat and wood that is not gerufa or ketuma. Presumably, the term tavshil is a food that has already reached a certain level of bishul, but the mishna nevertheless says that the prohibition of shehiya is applicable to it. The implication is that the Mishna disagrees with Chananya, and it does not allow shehiya on the stove which is not gerufa or ketuma, even for a tavshil which is cooked to the level of maakhal ben Derusai. The Gemara (36b), as we have said, suggests reading the mishna as relating to this prohibition (shehiya), but it also suggests an alternative possibility (hachazara), according to which the mishna does not argue with Chananya. According to the second possibility, the mishna does not deal with the prohibition of retaining a tavshil on the stove from before Shabbat; only the prohibition of replacing a tavshil on the stove on Shabbat itself is addressed, and only for this issue does the mishna say that even if the food is fully cooked, one may return it to an unswept, unsprinkled stove, as will be explained below.
 As for the dispute between Rashi and the Rambam about measuring maakhal ben Derusai, the Mishna Berura (253:38) writes that initially one should be stringent to follow the Rambams view and to retain on the fire only on a food that is half-cooked, but in a case of pressing need, one may be lenient and one may follow Rashis view and suffice with one-third cooked.
 The Peri Megadim (Eshel Avraham 253:41) still requires further analysis, but since the Chazon Ish has decided to be lenient and we are talking about rabbinical doubt, we have ruled in accordance with the lenient view.
 In this pot, there is an issue of hatmana, and we will deal with this in a future shiur.
 In fact, there are those who dispute the view of the Chazon Ish and believe that it is enough for the food to be raw at the time that we accept Shabbat, and there is no need that it be raw at sunset (see Penei Shabbat, ch. 253). Similarly, in the Or Le-Tziyon (Vol. I, ch. 21), we find that as long as the meat has not begun to soften, the dish is considered raw, and according to this, one may put a pot with raw meat on the fire even a great time before sunset, if the meat will not begin to soften until sunset.