Rabbi Mendel Agranovich
Introduction and General Concepts
In addition to the Torah's prohibition against cooking, our Sages instituted several additional prohibitions related to the prohibition against cooking on Shabbat. These are the following three prohibitions: leaving food on the fire from Friday, returning it to the fire on Shabbat, and insulating a pot.
First we will give brief definitions of these prohibitions, and then examine each one in detail.
The prohibition against “leaving food on the fire” means that food may not be left on an open flame from Friday, except in the cases our Sages specified as permissible. The reason is that although a person places the pot on the fire on Friday (when Shabbat prohibitions do not apply), a dish cooking on Shabbat nonetheless worries the woman of the house and makes her want to check how it is progressing. There is thus a concern that the man of the house or his wife will stir the coals (in the language of the Talmud), or, in modern terms, want to increase or adjust the flame beneath a dish important to the Shabbat meal. This need not be a conscious desire; quite the contrary, the Talmud (Shabbat, 18b) shows that it can happen automatically, since a person is accustomed to behaving this way: “I approach the pot, see what is happening, stir the coals so that it will simmer better or finish cooking.”
Next, we will consider the ways in which our Sages limited the scope of this prohibition. Clearly, this decree is related not only to the prohibition against cooking, but largely to the prohibition against kindling a fire on Shabbat.
The prohibition against returning food to the fire on Shabbat means that a pot taken off the fire before or during Shabbat may not be put back on the stove (even if the food is already fully cooked; otherwise, this would already fall under the Torah prohibition against cooking). The reason for this prohibition is that an action such as returning food to the fire is perceived as cooking in the eyes of others (the Ritva) or in our own eyes (the Ran). (In rabbinic terminology, this is expressed more simply: “it looks like cooking.” In whose eyes it looks this way is the subject of a dispute between the Ritva and the Ran, whose opinions we cited above.) Another explanation for this prohibition was offered by the great Rabbi Yaakov ben Meir (known as Rabbeinu Tam), the grandson of the great Rashi. He maintained that whenever a person wants to return food to the fire after it has cooled somewhat, even though it is already essentially cooked, a new concern arises: the homemaker may want to stir the coals so that the food warms up.
Both of these prohibitions reflect our Sages’ understanding of human psychology and their desire to protect a person from habitual behavior that could lead to an unintentional violation through force of habit. Because the person wants the result of the action, it constitutes a violation, even though it is unintentional. A sin-offering must be brought for it, since the person was merely distracted for a second and forgot that it was Shabbat.
The prohibition against insulating a pot is as follows.
1. On Shabbat, one may not wrap a pot in a blanket to keep it from cooling.
This prohibition, too, is rooted in the methods people use to reheat food and maintain its temperature when cooking over a fire and coals. Before placing a pot in a blanket or any other insulating material, one usually needs to heat it as much as possible so that it will retain its heat for as long as possible. The Talmud says (Shabbat, 34a) that one may not wrap a pot in materials that retain heat, because there is a concern that someone will want to bring the pot to a boil and will stir the coals to do so (even placing a cooled pot of soup on an existing fire, even a covered one, is a problem).
If anyone wishes to object that this works differently, I hasten to point out that I know the practice in this example from my own childhood. The fact is that I remember very well how my grandmother used to tuck a pot of buckwheat porridge into pillows and blankets, or wrap it in a towel. When I curiously asked why she was doing this, my grandmother said that she did not want to give my sister and father porridge that had been reheated repeatedly and dried out, but wanted to keep it hot until they arrived. Before placing the buckwheat porridge in a blanket, my grandmother would heat it once with some water, so that it would begin cooling from a higher temperature. And if we had not had gas, the fire would have had to be made stronger, as our Sages explain.
2. Even before Shabbat, one may not place a pot inside any material that adds heat while wrapping it for better insulation (for example, in decomposing olive pressings or lime [Mishnah]). A pot may not be wrapped in any insulating material or placed on a heater. The explanation we know for this is as follows. Even before Shabbat, a pot may not be insulated in a way that adds a small amount of energy, because a person might want to place the pot in a mixture of ash, coal, and earth, and stir an ember in the process. We see that this enactment is very broad: a pot may not be insulated with any material that adds energy to the system, even a small amount, because one might bury it in a pit with coals and earth and kindle an ember there. And this is what the whole problem comes down to? Here we see the breadth of our Sages’ understanding and the narrowness of our everyday thinking. It seems to us that such a remote concern should not make life more complicated for ourselves and all subsequent generations of the Jewish people. But if we understand how terrible the sin of even an unintentional violation of Shabbat is, how important it is to save a Jew from it even once, and how an ordinary person views the method of retaining heat in coals and earth, then, after weighing all the pros and cons, we will understand why the Sages enacted such a broad prohibition—a fence around the law.
As an example that very clearly illustrates the Sages’ perspective, my teacher, Rabbi Shlomo Breuer, would describe the following situation. When Rosh Hashanah falls on Shabbat, one may not blow the shofar. This is a law enacted by the Sages. The reason is that if even one Jew is eager to learn to blow the shofar, but does not know or forgets the law and takes the shofar into the street, carrying it 4 cubits in reshut harabim, he thereby violates a Torah law (and the same applies to the lulav on Sukkot and the Scroll of Esther on Purim). Let us think, our teacher would ask: how likely is it that such a person will be found? Now let us imagine: how much merit for the entire Jewish people’s fulfillment of the commandments lies on the other side of the scale? And all this at the most critical moment of the Heavenly Judgment of everything in the world! And on these scales, even one person tips the balance! What does a single sin mean, even an unintentional one?! It is worth setting aside a commandment for all time, for the entire people, to protect even one unlearned Jew from sin! My mentor’s voice still rings in my ears. We would weigh everything differently, but we do not have the right scales, while the Sages do, and that is precisely why we have a Torah commandment to heed them.
Let us return to the main topic of our article—the prohibition against leaving food on the fire before Shabbat begins, out of concern that the coals will be stirred on Shabbat. Obviously, there is no prohibition against cooking on Friday, but the concern that the fire will be made stronger is the reason for the prohibition. Accordingly, when this concern is absent, the prohibition is absent as well. Let us examine these cases.
The Talmud (Shabbat, 36b) records a dispute among the Sages. Chananya held that once food has been cooked to the stage of “Ben Derusai’s food” (half the cooking time or one third), there is no prohibition against leaving it on the fire before Shabbat so that it finishes cooking on Shabbat. We are no longer concerned that a person will stir the coals beneath the pot, because it will finish cooking in time for the evening meal even without this. The Sages, however, held that as long as heat improves the food’s flavor, we are concerned that the coals may be stirred by a homemaker who wants to improve the dish’s flavor.
Until food reaches the stage of “Ben Derusai’s food,” leaving it on the fire gives rise to this concern according to both Chananya and the Sages. If heat only makes the food worse, then even the Sages permit putting it on the fire before Shabbat. It is important to note that the Sages permitted only fully cooked food that deteriorates with further heating. In other words, the dispute concerns only food that has passed the stage of “Ben Derusai’s food” (even after it has finished cooking), provided that further cooking improves it.
In this dispute, the Mishnah Berurah holds that ideally one should try to follow the stricter opinion of the Sages, but if time is short, one may leave food on the fire if it is at least one-third cooked. The Chazon Ish held that one may follow Chananya’s opinion from the outset. The reason for this dispute is that throughout Jewish history, the opinions of all the great teachers of successive generations have been divided. The Rif, Rabbeinu Chananel, and the Rambam ruled that one must be stringent, following the Sages’ opinion, while Rashi and Tosafot held that one could rely on Chananya’s opinion. The Rosh summed up this dispute with the following statement: “Leave the Jews, who are devoted to the commandment, to enjoy Shabbat.” The Rosh meant that people who want to prepare delicious food for Shabbat continue cooking until the last moment, and therefore adopt the lenient view, relying on Chananya’s opinion. But may this be done from the outset? The Shulchan Aruch ruled that one should follow the Sages’ opinion, while the Rema ruled in accordance with Chananya’s opinion. The Chafetz Chaim (“Mishnah Berurah”) held that ideally one should follow the Sages’ opinion, while the Chazon Ish maintained that the Rosh’s statement attests to an accepted custom among the people that had become law. The Chafetz Chaim, however, explained that the Rosh simply did not consider it possible to object to people who relied on Chananya’s opinion, but we must tell those who ask us that they should be stringent, following the Sages’ opinion. Therefore, if we are discussing a situation in which a homemaker wants to leave food on an uncovered fire, the food should ideally be fully cooked (or one-third cooked after the fact), and then this is permitted.
In practice, however, people very rarely leave food on an uncovered fire. Why is that? The Talmud stipulates that if the coals are sprinkled with ash or completely raked out of the stove (the type of stove called a “kirah”—a two-burner stove in which a pot can be placed both on top and inside; [almost] all modern stoves are treated as equivalent to it), then even if the food has not yet reached the stage of “Ben Derusai’s food,” one may put it on the fire before Shabbat (even if the food is completely raw). Why is this so? “Magen Avraham” says, and “Mishnah Berurah” explains this law in the same way, that a person who sprinkles ash over the coals or rakes them out of the stove undergoes a change in mindset, because he has done something that runs counter to making the fire stronger. Even if the fire later flares up, “Magen Avraham” held that this is enough to allow food to be left on the fire. After this action, the concern that the coals will be stirred is no longer present, because the person has inwardly accepted that even if the food is not cooking through, he will not stir the coals. For this, it is enough to sprinkle even the smallest amount of ash over the coals, thereby damping them down.
When it comes to modern stoves, such as gas stoves, the accepted view is that all the Talmud’s laws apply to them in exactly the same way. How, then, can one sprinkle ash over the flame of a gas burner? The accepted solution to this problem is a sheet of steel or copper placed over the burners.
There is also the Shabbat hot plate—a heater whose heat output cannot be adjusted.
Practical conclusions:
Ideally, fully cooked food may be left on the fire on Friday, with no concern that the fire will be made stronger, since the dish is already cooked and the heat merely dries it out.
If the food is not yet one-third cooked, all opinions agree that it may not be left on an uncovered fire, but only on a fire covered with a sprinkling of ash (or on a metal sheet or a hot plate).
If the food is half cooked, the Chazon Ish permits leaving it on the fire from the outset, while “Mishnah Berurah” holds that one should ideally try not to do this, and should also place the pot on a hot plate or metal sheet.
If the food is fully cooked and additional heat only makes it worse, all opinions permit leaving it on the fire, but since the fire must be covered with ash if we wish to return the food to it, it is customary always to place food on a covered fire, that is, on a hot plate or metal sheet.
Shabbat shalom!