We've now covered how to prepare and serve hot food on Shabbat.1 In our last lesson on Bishul, we'll deal with a few remaining issues.

Activities Related to Food

Stirring the pot – Recall from our earlier lessons that, in halacha, there are many ways to increase the effect that heat has on food. You can raise the flame; cover the pot with a lid; wrap or insulate the food; and so on. One other way is to stir the food being cooked. This action, known as maygis, is not allowed on Shabbat, on the assumption that moving the food around will better distribute the heat, and this would be an act of Bishul.2

The problem of stirring applies when the food is hot and not fully cooked. The classic example would be stirring cholent cooking in a crock pot just after Shabbat began. Although the cholent is at least partially cooked by this time, it might not be fully cooked. It is certainly hot, and connected to its heat source.

Some Sages extend this prohibition to food that is fully cooked, if it is still connected to its heat source. It is good to avoid doing this as well.3

Only stirring or shaking the food is a problem. You are allowed to remove the food for serving, provided that the pot is not on the fire (Point A of the blech, as discussed in Lesson #22), and that you remove the food without any stirring action.4

Too Hot, Too Cold – A common situation we face during Shabbat meals is having a drink or liquid food that is either too hot or too cold for our taste. How do we deal with this within the boundaries of halacha?

  • "Too hot" – The normal way to cool off hot soup (or tea) is to add ice or cold water. We might instinctively think that this can't be done on Shabbat, because it seems that the hot soup, say, would 'cook' the ice, and this would violate the laws of Bishul. In fact, it is okay to put the ice in, since the soup bowl is, at worst, a 'second vessel',5 and the halacha says that water cannot be cooked in such a vessel.6

Note, though, that we cannot pour hot water over ice – say, putting a piece of ice in a teacup and then pouring in the tea – because of the prohibition on melting ice through a direct act (as discussed this in our lesson on Dosh #9), and also the problem of iruy kli rishon.

  • "Too cold" – Say you have some cold water that you'd like to heat up. An example: in the winter, the water coming from the tap is often quite cold. When it comes time to wash our hands before eating bread, we might want to take the chill out of the water by adding some hot water.7 Can we do this?

The answer is yes – so long as the hot water will not heat the cooler water to the temperature of Yad Soledet Bo (the temperature at which liquids become halachically 'cooked').8 This means that we need to take care that the volume of cold water is much greater than the volume of hot water.9

Another example: warming up a baby bottle. Babies prefer drinks that are not refrigerator-cold. So how do you take the chill out of a bottle that's been in the fridge? The most common solution is to pour some water from your urn into a mug or small bowl, and then immerse the bottle in that water. Again, we are using a 'second vessel' (the mug or bowl), and also the heat of the hot water is not even touching the liquid in the bottle.10

  • "Just right" – No halachot here; we just included it for the sake of completeness.

Non-Food Issues

Surprisingly enough, there are some Bishul issues outside the context of food.

First, we should be aware that Bishul can occur with any substance that will be physically changed by heat.11 Bringing metal to the point where it is red-hot is considered Bishul. This, incidentally, is one of the problems with turning on an incandescent light bulb on Shabbat: the filament becomes red-hot.

Hot Water Tank – There is also the issue of using hot water inside your home. When you turn on the hot water faucet, it of course comes out of the hot water heater. To maintain the water pressure, new cold water automatically gets sent to the heater. This new water will then become heated to a high temperature – in other words, halachically 'cooked'. So, we are not allowed to activate this process by using hot water from the tap.12

Solar Heat – In terms of the melacha of Bishul, solar heat is not considered "heat," since it is not a usual form of cooking.13

Therefore it is permitted to cook something directly in the sun. For example, one could use a magnifying glass to direct the solar heat to cook an egg.

A solar water heater is problematic, because typically it also has an electric component for use on a cloudy day. So that makes the entire system generally off-limits on Shabbat.14

Overall Review

What have we learned over six lessons on this most complex of melachot?

  • We began with the definition of Bishul: "using heat to change the physical structure of an object."

  • The threshold of Bishul is different for solids and liquids. For solid foods, cooking is achieved when the food is partially edible; for liquids, when they reach the temperature of yad soledet bo (113°F or 45°C).

  • Stirring a pot of food, putting a lid on a pot, and closing an oven door are all forbidden actions, as this will cause cooking to take place more rapidly.

  • "Cooking" can still occur when removed from the heat source. In this regard, there are three types of 'vessels':

    • First Vessel – the pot in which food is actually cooked. This will halachically cook anything that is placed in it (that has not already been cooked).
    • Second Vessel – When you transfer the food from this initial pot and place it in a bowl, that bowl becomes a 'second vessel'. Only water and oil can be placed in this, since all other things will become halachically cooked.
    • Third Vessel – here, items cannot become halachically cooked (at least according to one of the main opinions we discussed).
  • Iruy Kli Rishon – When pouring hot liquid from a first vessel onto solid, uncooked food, the outermost layer of the food will become cooked. When pouring hot liquid from a first vessel onto a cold liquid, whether or not an act of Bishul takes place will depend on the volume of each liquid.

  • There are certain exceptions where something gets the status of "first vessel": a ladle, and a hot solid food (davar gush) like a potato.

  • Once a food is cooked, it is permitted to reheat it. A cooked solid can be put into a first vessel (that's removed from the fire), whereas a cooked liquid that has cooled off to room temperature can only be put into a second vessel.

  • A food can be reheated only using the same method that was used to cook it in the first place: Something that was previously cooked may be reheated only via hot liquid, and something previously baked/roasted can be reheated only via dry heat.

  • There are three significant rabbinic decrees regarding Bishul:

    • She'hiyah – not leaving food on an open flame. We solve this problem by using a blech.
    • Chazarah – It is permitted to return food to the blech only on condition that when you remove the food, you: 1) intend to put it back, 2) continue to hold the pot, and 3) the food does not cool off before you return it.
    • Hatmanah – It is permitted to insulate food only if the wrapping does not completely cover the pot and/or food.
  • Cooked food may be taken from the refrigerator and reheated by placing it on top of a pot which is on a heat source.

  • Uncooked food can only be put in a place where the food will not reach the temperature of yad soledet bo (e.g. on a radiator).

  • There are also non-food applications of Bishul – e.g. bringing metal to the point where it is red-hot.

Congratulations! We've not only completed Bishul, but we've completed the entire 'Order of Bread' that we began way back in lesson #3. Our bread, so to speak, has just come out of the oven. Enjoy!


  1. It’s important to know that these lessons cover only the basic laws of Bishul. Once a person becomes comfortable with the basics, there is a great deal more that he or she can learn. Refer to the booklist cited in Lesson #1.
  2. Orach Chaim 318:18. The Hebrew term for this is kiruv Bishul – i.e., making the cooking happen more quickly.
  3. Rema – Orach Chaim 318:18, with Mishnah Berurah 113; 39 Melochos, p. 647. Ideally, one should have all food fully cooked before Shabbat.
  4. This is because removing the food is obviously not intended to better cook it. Mishnah Berurah 318:117; 39 Melochos, p. 647-48 and footnote 308.
  5. Recall the types of vessels from lesson #20. The soup bowl would be considered a ‘second vessel’ if the host served the soup straight from the pot (the ‘first vessel’) into the bowl. If the soup was first put into a tureen, and then into the individual bowls, the bowl would be only a ‘third vessel’. Some Sages say that nothing can become halachically cooked in a third vessel.
  6. Here we are only discussing water. The halacha will not be the same if you put most other substances into the soup bowl.
  7. As we’ll soon discuss, running the hot water from the tap is not allowed on Shabbat.
  8. On this concept, please go back to lesson #19 (our first one on Bishul).
  9. Mishnah Berurah 318:83; 39 Melochos, p. 652. Using the same logic, it is also okay to heat up food that is inside a baby’s bowl, where the bowl has a hollow bottom for water to be put into.
  10. Here’s something you may not have considered: Completely immersing the bottle in the hot water is a problem of hatmana! See 39 Melochos, p. 655-6 on this issue, and for other approaches to warming bottles.
  11. Take a look again at the definition of Bishul (in lesson #19).
  12. Orach Chaim 318:9; Shemirat Shabbat K’Hilchato 1:39; 39 Melochos, p. 639.
  13. Talmud – Shabbat 39a, Rashi s.v. “D’Shari”; Orach Chaim 318:3; 39 Melochos, p. 587-88.
  14. Shemirat Shabbat K’Hilchato 1:45 (127).