An oven that contracted tumah, how is it rendered tahor? One divides it into three [sections] and scrapes off the [clay] coating down to the ground. R’ Meir says: It is not necessary to scrape off the [clay] coating nor [is it necessary to divide it] down to the ground; rather, one reduces it from within [to less than] four handbreadths. R’ Shimon says: And it must be moved. [If] one divided it into two [sections], one large and one small, the larger [section] is tamei and the smaller [section] is tahor. [If] one divided it into three [sections], [such that] one [section] was as large as [the other] two, the larger one is tamei and the two smaller ones are tahor.

[If] one cut [the oven into] segments along its width, [each segment that is] less than four handbreadths is tahor. [If] one plastered it with clay, it becomes susceptible to tumah from when he heats it enough to bake sponge cakes in it. [If] one distanced the [clay] coating from it and placed sand or pebbles between them, of such [an oven] they said: A niddah and a woman who is tahor may bake in it and it is tahor.

An oven that came in pieces from the artisan’s workshop, and he made hoops for it, when he puts them on [the oven] it is [still] tahor [and then] it is tamei. [If] he removed its hoops, it is tahor. [If] he returned [the hoops] to [the oven] it is tahor. [If] he plastered it with clay it becomes susceptible to tumah, and he need not heat it, since it was already heated.

[If] one cut [the oven into] segments and placed sand between the segments, R’ Eliezer rules [it] tahor, but the Sages rule [it] tamei; this is the oven of the [coiled] serpent. Arabian cauldrons that one digs in the ground and plasters with clay: If the clay can stand on its own, it is tamei, but if not, it is tahor; and this is the oven of Ben Dinai.

An oven of stone or of metal is tahor, but [the metal oven] is tamei as a metal utensil. [If] it developed a hole [or] became damaged [or] cracked [and] one made a [clay] coating for it or a supplement of clay, it is tamei. How large must the hole be? [Large] enough for the flame to pass through. And the same applies to a stove. A stove of stone or of metal is tahor, but [the metal stove] is tamei as a metal utensil. [If] it developed a hole [or] became damaged [or] cracked [and] one made feet for it, it is tamei. If one plastered it with clay, whether on the inside or on the outside, it is tahor. R’ Yehudah says: On the inside it is tamei, but on the outside it is tahor.

[If] one assembled three feet upon the ground and joined them with clay so that he could set the pot on top of them, [this makeshift stove] is tamei. [If] one affixed three nails into the ground so that he could set the pot on top of them, even though he fashioned a place at the top of [this makeshift stove] for the pot to rest, it is tahor. [If] one made two stones into a stove and joined them with clay, it is tamei. R’ Yehudah rules [it] tahor until he makes a third [stone] or until he places [the stove] near a wall. [If] one [stone was joined] with clay and one was not [joined] with clay, it is tahor.

[If] one set a pot upon a stone and upon an oven, [or] upon [a stone] and upon a stove, [or] upon [a stone] and upon a kupach, it is tamei. [If one set a pot] upon [a stone] and upon a [second] stone, [or] upon [a stone] and upon the bedrock, [or] upon [a stone] and upon a wall, it is tahor. And this was the stove of the nezirim in Jerusalem that was [built] against the bedrock. The stove of butchers: When he places one stone alongside [another] stone, [and] one of them became tamei, the others do not become tamei.

Three stones were made into two stoves: [If] one of the outer [stones] became tamei, [the part of] the middle [stone] that serves the tamei [stone] is tamei, [and the part] that serves the tahor [stone] is tahor. [If] the tahor [stone] was removed, the middle [stone] becomes entirely tamei. [If] the tamei [stone] was removed, the middle [stone] becomes entirely tahor. [If] the two outer [stones] became tamei: If the middle [stone] was large, one allots as much as is needed to set [a pot] on either side and the remainder is tahor; but if it was small, it is entirely tamei. [If] the middle [stone] was removed: If a large cauldron can be set upon [the stove], it is tamei. If [the stone] was returned, it is tahor. If [the stone] was plastered with clay, it will be susceptible to tumah from when one heats it enough to cook the egg on it.

Two stones were made into a stove and became tamei, [and then] one placed a stone next to [one of the tamei stones] on one side, and a stone next to [the other tamei stone] on the other side: Half of [one tamei stone] is tamei and half of it is tahor, and half of [the other tamei stone] is tamei and half of it is tahor. [If] the tahor [stones] were removed, the others return to their state of tumah.

The stove bases of householders which collapsed: [If it was] less than three handbreadths, it is tamei, since one heats it from below and the pot up above will cook, [but if it was] more than that, it is tahor. [If] one inserted a stone or a pebble it is tahor. [If] he plastered it with clay, it will be susceptible to tumah from then on. [And] this was the response of R’ Yehudah regarding the oven that was placed over the mouth of a pit, or over the mouth of a cistern.

A shelf that has a receptacle for pots is tahor as a stove but tamei as a utensil with a receptacle. [Regarding] its sides: That which touches [the walls] is not tamei as a stove. [Regarding] its wide [side]: R’ Meir rules [it] tahor and R’ Yehudah rules [it] tamei. The same applies if one turns over a basket and builds a stove on it.

A stove that split along its length is tahor, but [if it split] along its width it is tamei. A kupach that split either along its length or along its width is tahor. The courtyard of a stove: When it is three fingerbreadths high it contracts tumah via contact and via airspace, [but if it is] less than this [then] it contracts tumah via contact but does not contract tumah via airspace. How is it measured? R’ Yishmael says: One places the spit from top to bottom and [the area] opposite [the spit] contracts tumah via airspace. R’ Eliezer ben Yaakov says: [If] the stove became tamei, the courtyard becomes tamei, [but if] the courtyard became tamei, the stove does not become tamei.