The study of the thirty-sixth folio, second side of Shabbat is dedicated by Benjamin Stavsky for a complete recovery for all the ill of Israel, a healing of the soul and a healing of the body, speedily in our days. This study marks the beginning of a new chapter in Masechet Shabbat, known as Perek Kirah. Although the current schedule focuses on the thirty-seventh folio, we must return to the beginning of the chapter to establish the necessary conceptual foundation.
To understand the discussions ahead, we must first define the physical and legal terminology involved. An oven, referred to as a oven, was a rectangular heating device with space on top for two cooking pots. The heat source consisted of coals placed inside the structure. The primary halachic concepts we will explore are leaving food on the fire and returning food to the fire. Leaving food refers to the act of allowing food to remain on the oven as the Sabbath begins on the eve of the Sabbath. Returning food refers to the act of placing a pot back onto the oven on the Sabbath itself after it has been removed. These two categories—leaving food and returning food—carry distinct rules and concerns.
A fundamental dispute exists between the Chakhamim and Chananya regarding how to interpret the Mishna. According to the Sages, the restrictions mentioned in the Mishna refer even to leaving food on the eve of the Sabbath. They rule that one may not leave food on an oven that still contains active coals—a state described as not being cleared. The reason for this prohibition is the concern that one might come to stoke the coals on the Sabbath to increase the heat. However, Chananya argues that the prohibition of leaving food does not apply if the food has already reached a basic level of edibility, known as the food of Ben Drosai. For Chananya, the restrictive language of the Mishna refers only to returning food on the Sabbath itself. He maintains that on the eve of the Sabbath, one may leave food even on an oven that has not been cleared of coals, provided it is partially cooked.
Another pivotal layer of understanding comes from the early commentators, specifically Rashi. In the previous chapter, we learned the laws of insulation, which involves wrapping a pot to retain its heat. It is universally accepted that insulating a pot with a heat-generating substance is forbidden even on the eve of the Sabbath. Rashi views the laws of the oven as an extension of the laws of insulation. He explains that leaving food on an oven with coals is forbidden because the coals generate heat, making it similar to the prohibition of insulating with heat-generating materials like hot cinders. While many other early commentators, including those in Tosafot, disagree and treat leaving food and insulation as two entirely different subjects, Rashi maintains that they share the same underlying concern: the fear that a person might stoke the coals.
The Mishna begins by distinguishing between different types of fuel. If an oven was fueled with straw or stubble, which are highly flammable and burn away without leaving lasting coals, one may place cooked food on it. In this case, there is no concern about stoking. However, if the oven was fueled with wood or sesame refuse—materials that produce long-lasting coals—one may not place a pot on it unless the coals have been cleared out or covered with ash. Covering the coals with ash, a process called covering, demonstrates that the individual has no interest in increasing the heat, thereby removing the concern of stoking. Rashi emphasizes that the purpose of covering the coals is to cool them down.
The Mishna further records a dispute between Beit Shammai and Beit Hillel regarding what may be left on an oven that has been cleared or covered. Beit Shammai takes a stringent view, permitting only hot water but forbidding cooked food. They are concerned that even on a cleared oven, a person might stoke any remaining sparks to further cook the food. Since food improves as it shrinks and cooks further, the temptation to stoke is high. Water, conversely, evaporates and diminishes when heated further, so there is no incentive to stoke the coals. Beit Hillel rules more leniently, allowing both hot water and cooked food to be left on a cleared or covered oven, as they do not extend the prohibition to such cases.
A second dispute between these schools concerns returning food on the Sabbath. Beit Shammai rules that while one may remove a pot from the oven on the Sabbath, one may never return it, even if the oven is cleared or covered. Beit Hillel permits returning the pot to a cleared or covered oven. The underlying issue with returning food is that it may look like one is beginning a new act of cooking. However, Beit Hillel holds that if the oven is cleared or covered, it no longer looks like the normal way of cooking, and therefore it is permitted for food that is already fully cooked.
The Gemara analyzes the structure of the Mishna to determine whether the opening restriction "one shall not place" refers to leaving food or returning food. If it refers to leaving food, the flow of the Mishna is logical: it first discusses the rules of leaving food, then the dispute between Beit Shammai and Beit Hillel regarding leaving food, and finally their dispute regarding returning food. If the opening refers only to returning food, the Gemara points out a potential redundancy in the Mishna's language. To resolve this, the Gemara suggests the Mishna might be missing certain words and should be read as follows: on an oven of straw, one may return food; on an oven of wood, one may not return food unless it is cleared, but leaving food is permitted regardless. Under this reading, the subsequent disputes between Beit Shammai and Beit Hillel clarify that even when leaving food is permitted, they disagree on what types of food are included, and they further disagree on the very permissibility of returning food. This analytical journey continues as we move into the thirty-seventh folio.