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Shiur #09: Cooking in a Keli Sheni

  • Harav Baruch Gigi
The Israel Koschitzky Virtual Beit Midrash

The Laws of Shabbat
Yeshivat Har Etzion

Shiur #09: Cooking in a Keli Sheni


By HaRav Baruch Gigi

Translated by David Silverberg



The Principle of Keli Sheni Eino Mevashel


            The Mishna in Masekhet Shabbat (42a) allows adding spices into a keli sheni – the utensil into which the food is poured from the original utensil in which it was cooked.  From here it is learned that keli sheni eino mevashel – a keli sheni is incapable of effectuating the halakhic process of bishul.  This principle emerges also from an earlier sugya (40b), where Rebbi instructed his student, "Place it [a jug of oil] in a keli sheni [filled with water, to warm it] and give [it to me]."  The Gemara infers from this incident that bishul cannot occur in a keli sheni.  The Rishonim struggled to identify the precise point of distinction between a keli rishon and keli sheni, and developed different approaches in dealing with this question.


            We will begin with the Yerei'im, who writes:


Bishul depends neither on a keli rishon nor on a keli sheni, but rather on the item being cooked.  At times it is a soft item and can be cooked even in a keli sheni, whereas there are hard items that cannot be cooked even in a keli rishon, and some items are cooked in a keli rishon but not in a keli sheni… A person must therefore ensure not to place any item in a keli sheni or even in a keli shelishi [the utensil into which the food was poured from a keli sheni] at the point of yad soledet bo [where one's hand would instinctively recoil on contact], for we are unsure regarding soft and hard items, which are cooked in a keli sheni and which are not cooked [in a keli sheni].


In the Yerei'im's view, the fundamental distinction is not between the different types of utensils, but rather between different types of foods – hard food items and soft food items.  Thus, soft foods may not be cooked even in a keli shelishi at a temperature of yad soledet bo.


            The Rashba, by contrast, maintains that Chazal drew a clear distinction between a keli rishon and keli sheni.  He writes (chiddushim, Shabbat 40b s.v. meivi adam), "They mentioned keli rishon and keli sheni only because the first is capable of cooking, and the other is not capable of cooking."[1]  In light of this approach, the Rashba must deal with the empirical fact that cold water added to hot water in a keli sheni indeed reaches the level of yad soledet bo, seemingly proving that even a keli sheni is capable of cooking.  Commenting on a later sugya (42a s.v. be-davar), the Rashba offers the following explanation:


Since it is a keli sheni, it will always be permissible, since it reaches only lukewarm [levels].  And even if the water was [at the point of] yad soledet ba-hen after cold water was mixed into it, this results not from the cold water in it becoming yad soledet, but rather from the original water, which did not cool [through its contact with the cold water].


Though it is difficult to fully understand this passage, the Rashba's intention is clear: the reality of yad soledet emerges not from the cold water that becomes hot, but rather from the hot water, which does not become cold.[2]


            Tosefot (40b s.v. u-shema mina) develop a different approach:


It is difficult: How does a keli sheni differ from a keli rishon?  If [it is at a temperature of] yad soledet, then even a keli sheni [is capable of cooking], and if it is not [at the point of] yad soledet, then even a keli rishon is not capable of cooking!  We might say that because a keli rishon sat over a fire, its walls are hot and it retains its heat for an extended period.  They [Chazal] therefore established the criterion that so long as [it is at the point of] yad soledet bo, it is forbidden [to cook in the keli rishon].  But a keli sheni – even when it is yad soledet bo it is permissible [to cook in it], because its walls are not hot and it gradually cools.


In posing their question, Tosefot advance the claim that the possibility of bishul occurring in any utensil should depend solely on the factor of yad soledet bo, and not on whether we deal with a keli rishon or keli sheni, on the assumption that level of heat is the determining factor.  This assumption, which Tosefot ultimately dismiss, bears resemblance to the Yerei'im's position, which sees no fundamental difference between the various utensils.  And this assumption is identical to a view recorded in the Yerushalmi (3:4): "Everyone agrees that it is permissible in a keli sheni.  Wherein lies the difference between a keli rishon and keli sheni?  Rabbi Yossi said: Here, one's hand would recoil; here, one's hand would not recoil."  According to this view, the distinction pertains only to the level of heat.

            In their answer, Tosefot assert that the criterion that defines bishul involves not merely the current level of heat, but also the period of time for which this level is retained, and the walls of a keli sheni cool at a faster rate than those of a keli rishon.  In short, bishul is a function of a prolonged period of heat.


            But Tosefot's answer does not resolve the problem completely.  It is possible for a keli sheni to be at a relatively high temperature and lose its heat slowly either because of its narrow opening which allows limited exposure to air, or due to its thick insulation.  We might therefore explain that Tosefot refers not simply to an empirical factor, but rather to a halakhic factor.  In their view, bishul requires a heat source, and a keli sheni, which generally loses its heat quickly, is not generally perceived as a cooking utensil.  Therefore, Halakha likewise does not consider it "fire" for purposes of bishul, except in those rare instances where people generally use a keli sheni for this purpose, such as in the case of kulias ha-ispenin (a type of salty fish), which we have discussed on several occasions in earlier shiurim.


            We might draw proof to this theory from the Rambam's view, in light of the difficulties that arise from his comments regarding this issue.  The Rambam writes in Hilkhot Shabbat (22:6):


Similarly, a boiling pot, even though one removed it from the fire, one may not add spices to it, but he may add to it salt, because salt is cooked only over a large fire.  If one poured the food from a pot to a bowl, then even though it is boiling in the bowl, it is permissible to add spices to the bowl, for a keli sheni is incapable of cooking.


In the context of the laws of ma'aser, there is a rule, "Bishul kovei'a le-ma'aser."  This means that whereas generally one may partake of food that has yet be tithed for an akhilat arai (a quick snack), the process of cooking automatically defines any subsequent eating of that food as an akhilat keva (an established meal), which is forbidden before tithing.  Accordingly, the Rambam writes (Hilkhot Ma'aser 3:15):


Once oil drops down into the trough [of the olive press] – even though it already dropped down, one may take [oil] from the bale, press-beam or boards and place it into food in a small bowl or serving dish, even though it is hot, because it is not cooked in a keli sheni.  But if it was exceedingly hot, such that it would burn a hand, one may not place it [the oil] into it [the bowl or serving dish] because it would cook.


The Rambam rules that the point when the oil drops into the trough of the press marks the gemar melakha – the final stage of the oil's preparation.  Nevertheless, he permits placing oil into a keli sheni without tithing it, since the oil is not cooked as a result, and this therefore would not constitute akhilat keva.  If, however, the food/liquid in the keli sheni is at a high temperature, such that one's hand would burn on contact, we deem the keli sheni capable of cooking the oil, and one may therefore not eat the oil in this fashion without first taking ma'aser.


            This ruling appears to contradict the Rambam's comments in Hilkhot Shabbat.  With regard to the prohibition of bishul on Shabbat, the Rambam rules that a keli sheni does not effect bishul even if its contents are still boiling, whereas with respect to ma'aser he writes that if the contents can burn a hand – which presumably occurs at a lower temperature than the boiling point – the keli sheni is capable of cooking.


            It would appear that in the Rambam's view, a keli sheni generally does not have the capacity to cook, unless it is exceptionally hot, at the point where one's hand would be burned on contact.  In Hilkhot Ma'aser, we deal with the empirical question of whether cooking actually occurs, and one may therefore eat oil as an akhilat arai without tithing in a regular keli sheni, but not in an exceptionally hot keli sheni, at the point of yad nikhveit (where one's hand would burn).  With respect to Shabbat, however, a keli sheni does not accomplish bishul even at the boiling point, because a keli sheni cannot be classified as "fire" for purposes of the melakha of bishul, except in the case of kulias ha-ispenin, which is normally prepared in this fashion, and a keli sheni would thus qualify as "fire" in that particular instance.[3]


Summary of the Rishonim's Positions


            We have thus encountered several different approaches in explaining the reason why a keli rishon is deemed incapable of accomplishing bishul:


  1. Because of its low level of heat (Yerushalmi – "ein yad soledet bo").
  2. It does not retain its heat for a prolonged period of time (Tosefot – "it gradually cools").
  3. It is not defined as "fire" (our explanation of Tosefot and the Rambam).
  4. It depends on the type of food (Yerei'im).
  5. Practically speaking, it is never capable of cooking (Rashba – this was Chazal's empirical assessment).


Details Concerning Bishul in a Keli Sheni


1. Kalei Bishul – Easily Cooked Foods


            The Yerei'im, as cited above, wrote that one may not cook any food in a keli sheni unless the Gemara specifically speaks of that food as incapable of being cooked in a keli sheni.  We cannot ascertain the status of any other food vis-א-vis bishul in a keli sheni, and one must therefore refrain from cooking in it in a keli sheni.  The Ran wrote that even in a keli rishon we are uncertain which foods are subject to bishul and which are not, and we therefore refrain from placing any foods in a keli rishon.  It stands to reason that the Ran applied this stringency only to a keli rishon; in a keli sheni, however, the Ran would allow us to assume that it does not effectuate bishul, except in the case of kulias ha-ispenin, and, according to one view in the Gemara (42b), salt.


            The Tur (318) cites the Yerei'im's stringent position that a previously baked food is subject to bishul, and that one may not place bread even in a keli sheni at the level of yad soledet bo.  He then disputes the second halakha, which assumes that bishul can occur in a keli sheni.  He writes:


Rabbi Eliezer of Metz wrote, "Even though bishul cannot occur after [a previous] bishul when dealing with a dry food item, an item that had been baked or roasted is subject to bishul if one cooks it afterwards in liquid.  It is [therefore] forbidden to place bread even into a keli sheni [at the point of] yad soledet bo."  But this is very difficult – why would they forbid [this] in a keli sheni?  He perhaps compared it [bread] to salt, which the Gemara says – according to one view – can cook even in a keli sheni.  But it does not seem correct that it should be forbidden in a keli sheni."


2. Which Foods are Considered Kalei Ha-bishul?


            We mentioned earlier that the fish called kulias ha-ispenin, as well as – according to one view in the Gemara – salt, can be cooked in a keli sheni.  The Chazon Ish (Shabbat 52:19) wrote that eggs likewise belong to this category of kalei ha-bishul (items that are easily cooked), and one may therefore not boil an egg in a keli sheni.  He arrives at this theory based on an earlier sugya (38b), which considers roasting an egg alongside a hot kettle a Torah violation of bishul.  According to the Chazon Ish, the Gemara here seeks to establish that cooking kalei ha-bishul constitutes a Torah violation, and thus eggs are invoked as an example of kalei ha-bishul.  The work Pitchei Da'at cites Rav Yaakov Yisrael Fisher as allowing, strictly speaking, placing an egg in a keli sheni, though even he advises against doing so.


            According to the Yerei'im, we must suspect every item of being among the kalei ha-bishul, with the exception of beef, spices, water and oil.


            What about other liquids, besides water and oil?  From the Shulchan Arukh (318:13) it appears that other liquids are not deemed kalei ha-bishul, and the Mishna Berura makes no comment on the Shulchan Arukh's ruling.  Elsewhere in this siman, however, the Shulchan Arukh appears to indicate that we must, indeed, treat other liquids as possibly in the category of kalei ha-bishul.  In any event, when dealing with liquids that were cooked and then cooled, we may allow placing them in a keli sheni, taking into account the view among the Rishonim that the rule of ein bishul achar bishul (foods are not subject to bishul if they had been previously cooked) applies even to liquids.  Practically speaking, then, one may add cold pasteurized milk to a cup of coffee (since the milk has already been cooked, and the coffee cup is a keli sheni).


            The Chazon Ish held that strictly speaking, we need not consider every food item potentially of the kalei ha-bishul type.  At most, he maintained, we should apply this stringency only to bread, which the Yerei'im and Semag specifically mentioned.  He concluded, however, that common practice is to forbid cooking all foods in a keli sheni, though he allowed placing lemon juice in a keli sheni.


3. A Keli Sheni at the Point of Yad Nikhveit


            The Binat Adam writes in the work Sha'arei Tzedek, "It is very difficult that all the geonim…did not bring the Rambam's comments in Hilkhot Ma'aserot 3:15, where he wrote explicitly that if one's hand would be burned in a keli sheni – it is capable of cooking."  We have already seen that the Rambam distinguishes in this regard between the laws of Shabbat and the laws of ma'aser; with respect to bishul on Shabbat, cooking is permitted in a keli sheni even if its contents are boiling, as the Rambam writes explicitly in Hilkhot Shabbat (22:6).


            The Binat Adam drew support for his position from the aforementioned sugya in the Yerushalmi, Masekhet Ma'aserot, and from a sugya in the Bavli (Shabbat 42a) concerning a bathtub.  The Tur wrote that although a tub is treated as a keli sheni, one should nevertheless consider its water capable of cooking because of its particularly high temperature.  According to the Binat Adam, this applies equally to every keli sheni at the level of yad nikhveit.  By contrast, the Shevitat Ha-Shabbat (introduction to Mevashel section, 10) permits cooking in a keli sheni, regardless of its heat.


            The Acharonim generally ruled stringently in cases of yad nikhveit (see Mishna Berura 318:48).  The Chazon Ish, however, claimed that the Bavli disagrees with the Yerushalmi on this point, but conceded that as a practical matter one should not be lenient in this regard given the severity of Shabbat.  In practice, then, one should be stringent in cases of a keli sheni at the point of yad nikhveit, but be-di'avad (after the fact) one may lenient.


4. Davar Gush – Solid Foods in a Keli Sheni


            In the Yoreh Dei'a section of the Shulchan Arukh, the Acharonim debate the issue of whether a davar gush (solid food item) in a keli sheni absorbs and emits taste of forbidden foods.  The Rama (Y.D. 94:7) rules leniently, that taste is neither absorbed nor emitted in a keli sheni.  The Shakh (94:30), however, disagreed, and wrote, "Even in a keli sheni it is treated like a keli rishon so long as yad soledet bo, and it requires hag'ala [immersion in hot water], since it is a solid item."  This is also the view of the Maharshal, that a dry food – such as a piece of meat – transfers taste so long as its temperature is at a level of yad soledet bo, regardless of whether we deal with a keli rishon or keli sheni.


            The Peri Megadim discusses whether this stringency applies as well to the issue of bishul on Shabbat.  The Magen Avraham (318:45) rules that it indeed applies with regard to bishul, and a davar gush is capable of effecting bishul even in a keli sheni.  The Mishna Berura writes that be-di'avad, one may rely on those authorities who rule leniently on this issue:


Several poskim maintain that a solid food is capable of cooking so long as yad soledet bo, even in a keli sheni.  Nevertheless, be-di'avad, one need not forbid [the food] if it is placed in a keli sheni, as we may rely on the poskim [who hold] that a keli sheni is not capable of cooking under any circumstances.


Rav Moshe Feinstein (Iggerot Moshe 4:74) addresses the question of placing ketchup on a hot piece of meat in a keli sheni:


As for the final halakha, it would seem that one is permitted to place ketchup on boiling meat that had been placed in a keli sheni… But here, the stringency that a liquid is subject to bishul after having been previously cooked is but an additional stringency, for the most prominent poskim hold that even regarding liquids ein bishul achar bishul, and this is indeed the Rama's final decision – that this is the practice, and he rules stringently only if it has completely cooled.  And also the stringency regarding a davar gush, considering it like it is boiling even in a keli sheni, is disputed by many, including the Rama… Therefore, even this law, despite the fact that the Shakh in 105:8 follows the Maharshal, as does the Magen Avraham (45), we should not consider this a balanced safek such that since we cannot definitively rule leniently we must be stringent.  You are therefore correct that one need not follow these two stringencies, even with regard to the prohibitions of Shabbat.


5. Ladles


            Earlier we cited Tosefot's approach (40b) in explaining the difference between a keli rishon and keli sheni, claiming that the walls of a keli rishon retain their heat, whereas the walls of a keli sheni lose their heat and the utensil thus cools.  The Taz (Y.D. 92:30) inferred from Tosefot that a ladle, which one places into a keli rishon to draw its contents and then pours into a bowl, has the status of a keli rishon.  He notes that others disagree and treat ladles as a keli sheni.  The Mishna Berura (318:87) comments on this issue:


Something is considered a keli sheni when a keli rishon, in which the hot food was boiled, is poured into this utensil; it is permissible [to cook in it] even at the level of yad soledet bo.  But if one draws with an empty utensil from a keli rishon, some views hold it has the status of a keli rishon, particularly if he leaves the empty utensil in it until it boils – then it is certainly considered a keli rishon.


Earlier (318:45), however, the Mishna Berura implies that he considers the ladle a keli sheni: "But if one wishes to put bread [in soup], he should wait until the soup is no longer yad soledet, or, he should at least draw [the soup] from the pot with a spoon [= a ladle] so that the bowl will be a keli shelishi."  We might explain the Mishna Berura's position as requiring one to optimally follow the stringent position, considering the ladle a keli rishon.  However, where one wishes to place a previously baked item in hot liquid, in which case we are generally concerned for the Yerei'im's view forbidding placing bread even in a keli sheni, we may rely on the position that treats the ladle as a keli sheni, such that the bowl would be considered a keli shelishi.


            This halakha essentially results from a sefeik-sefeika (a "double uncertainty"): perhaps Halakha follows the view that baked foods are not subject to bishul, and even if bishul indeed applies to such foods, perhaps we accept the opinion that a ladle constitutes a keli sheni, in which case one would be allowed to place bread in his bowl, which would be considered a keli shelishi.[4]


6. "Mechzei Ke-mevashel" in a Keli Sheni


            Tosefot (Shabbat 39a s.v. kol) comment:


The Ri says that one may not soak [food] even in a keli sheni, because since the water is hot, it gives the appearance of cooking ["mechzei ke-mevashel"].  And although the Mishna later (42b) states, "but one may add [spices] to the bowl or serving dish," this applies only to spices, which are made [for the specific purpose] of adding flavor to [the food in] the pot, and it does not give the appearance of cooking.  Or, one may indeed soak it, since we deal with a keli sheni, and it [the Mishna] mentions rinsing [rather than soaking] to teach us that even rinsing constitutes the final stage of preparation in the cases of mali'ach ha-yashan and kulias ha-ispenin.


Tosefot thus advance two approaches with regard to keli sheni.  The first approach maintains that although bishul cannot occur in a keli sheni, one may not place foods in a keli sheni because it gives the appearance of cooking; spices, however, which serve merely to add flavor, may be placed in a keli sheni.  Tosefot draw their novel theory from the Mishna's comment, "Any food that had not been cooked in hot water before Shabbat may not be soaked in hot water [on Shabbat], but may be rinsed in hot water [on Shabbat]."  "Rinsing" here refers to pouring hot water from a keli sheni, indicating that raw food may not be soaked in a keli sheni.  On this basis, Tosefot establish that the principle of mechzei ke-mevashel applies to cooking in a keli sheni.  In their second approach, however, Tosefot explain that the Mishna seeks to emphasize that even pouring is forbidden in the cases of mali'ach ha-yashan and kulias ha-ispenin; other foods, by contrast, may indeed be soaked even in a keli sheni, since bishul cannot occur in a keli sheni.


            The Meiri, in his comments to the Mishna, explains that the Mishna does not refer to a food that had not been cooked at all before Shabbat and is thus completely inedible.  Rather, it deals with salty meat that can be eaten with difficulty even without rinsing.  The Meiri explains that the Mishna here allows pouring water from a keli rishon onto the meat, but not soaking it.  He explains:


Any food that had not been cooked in hot water before Shabbat, and is rather eaten on Shabbat with difficulty without cooking, such as exceptionally salty meat, may be rinsed in hot water on Shabbat, and we do not say that its rinsing amounts to cooking it, for even rinsing does not suffice for eating it comfortably, without any difficulty.  "But it may not be soaked" – meaning, for an hour or a half-hour, because it soaking – given that it is done in a keli rishon – cooks it somewhat.  "Except for mali'ach ha-yashan" – meaning, from the previous year – "and kulias ha-ispenin" – which is a fish that is eaten by rinsing it in hot water.  In all these cases, they [the food items] are forbidden even with only rinsing, because even during the week their rinsing is how they are cooked.


According to his reading, the Mishna does not deal with a keli sheni at all, and there is thus no basis for Tosefot's stringent position.


            As for the final halakha, the Magen Avraham (318:15) rules stringently on the matter, and this is the conclusion of the Mishna Berura (318:34), despite the fact that neither the Shulchan Arukh nor the Rama brings this halakha.  The Iglei Tal, by contrast, accepts the lenient view.




  1. The Rashba there objects to Rashi's text in the sugya, according to which "hefeshero zehu bishulo" – warming oil constitutes bishul, and yet one is permitted to place the jug of oil in a keli sheni because a keli sheni is not subject to bishul; we will elaborate on his view later.  The Rashba found this approach untenable, because the entire distinction between the various utensils stems from Chazal's assessment that a keli sheni is incapable of cooking.  Hence, if warming oil indeed constitutes bishul, it would be forbidden even in a keli sheni, which is capable of warming oil.  The Rashba therefore adopts the alternate text of the Gemara, which reads, "hefshero lo zehu bishulo."
  2. After all, according to the Rashba, Chazal very clearly determined that a keli sheni does not have the capacity to cook, and thus the empirical reality cannot indicate otherwise.
  3. The Radbaz, in his commentary to Hilkhot Ma'aser, answers that generally a keli sheni is incapable of cooking, but with regard to ma'aser, a keli sheni at the level of yad nikhveit can effect bishul, since this completes the oil's preparation for consumption, such that it becomes obligated in ma'aser.  He drew support for this theory from the Yerushalmi (Ma'aserot 1:7), which commented that where ein ha-yad sholetet (which we will define shortly), a keli sheni is halakhically no different from a keli rishon.  The Radbaz appeared to have understood the term ein ha-yad sholetet as referring to the heat level of yad nikhveit, thus proving that at this level a keli rishon and keli sheni are equivalent.  Generally, however, the term ein ha-yad sholetet refers to the level of yad soledet, where one's hand would recoil on contact, and not the heat of yad nikhveit.  The Mahari Kurkus indeed explained the Yerushalmi as referring to yad soledet, but he understood the Rambam's ruling concerning the level of yad nikhveit as speaking of yad soledet.  These readings are difficult to accept.  In general, the Yerushami's remarks concerning the distinction between keli rishon and keli rishon appear to relate to the sugyot in Masekhet Shabbat, and don't really belong in Masekhet Ma'aserot.
  4. The Chazon Ish (O.C. 122:3) distinguished between a ladle placed in a keli rishon over the fire, which should be treated stringently, and a ladle used in a keli rishon off the fire, which may be treated as a keli sheni.  Elsewhere (Y.D. 32) he wrote that one should treat ladles as a keli rishon under all circumstances.