Kelim, Chapter Five, Mishnah Three
1) The crown of a double stove is clean.
2) The fender around an oven: if it is four handbreadths high it contracts impurity by contact and through its air-space, but if it was lower it is clean.
3) If it was joined to it, even if only by three stones, it is unclean.
4) The place [on the stove] for the oil cruse, the spice-pot, and the lamp contract impurity by contact but not through their air-space, the words of Rabbi Meir.
a) Rabbi Ishmael rules that they are clean.
Section one: The crown is like a lid for the stove. It was placed on top of the hole to keep the heat in. Since it is unattached, it is unaffected by the impurity of the stove.
Section two: The fender around the oven is not attached to the oven. Some commentators explain that the purpose of this structure was to hold bread after it had been removed from the oven. If this fender is four handbreadths high, which is the minimum height of the oven, it is susceptible to the impurity of the oven. Thus an oven which is rendered impure by a defiling agent which comes into contact with it or enters its air-space will cause the fender to be impure. However, if it is lower than the oven than it is not susceptible to impurity.
Section three: In all cases if the fender was joined to the oven, then it is susceptible to the oven’s impurity because it is part of the oven.
Section four: On the stove’s outer walls were compartments to hold the oil cruse, the spice-pot and the lamp. However, they are only susceptible to impurity if the oven came into actual contact with a defiling agent. If an impurity came into the oven’s air-space, while the oven is impure the compartments remain pure. This is the opinion of Rabbi Meir. Rabbi Ishmael holds that the compartments are independent of the stove and therefore unaffected by the stove’s impurity.