[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.