Keilim 8:4-5

Keilim 8:4

Regarding a pot that is placed in an oven, if a sheretz (vermin) is in the oven, the pot remains ritually clean. This is because an earthenware vessel doesn’t render vessels unclean. If there’s moisture in the oven, the moisture in rendered unclean and conveys ritual impurity. It’s as if the pot says to the moisture, “The oven that made you unclean didn’t make me unclean, but you did.”

Keilim 8:5

If a chicken swallowed a sheretz and then fell into an oven’s airspace, the oven remains ritually clean, but if the chicken died, the oven is rendered unclean (i.e., only a living animal impedes the transmission of ritual impurity). If the sheretz is found in the oven, bread that was in the oven is a second degree of ritual impurity because the chain of transmission begins with the oven (i.e., from the sheretz to the oven – a first degree of impurity – to the bread).