Zevachim 3B

אם הציל במת חמור ⁠– שכן חלוקה באוהלין, תציל בכלי חרש הקל ⁠– שאין חלוקין באוהלין.

If a partition protects an item from impurity imparted by a corpse, which is severe, this is only because such impurity is unique in that it is imparted to that which is in the same tent, i.e., under the same roof, and tents are divided by partitions. If so, should a partition protect food from impurity imparted in an earthenware vessel, which, although mild, is not divided by partitions, like tents are?

התינח לרבנן; לרבי אליעזר מאי איכא למימר?

The Talmud notes: The comparison between non-sacred meat vis-à-vis offerings and a partition in an earthenware vessel works out well according to the opinion of the Rabbis, who hold that a partition does not prevent transmission of impurity inside an earthenware vessel. But according to the opinion of R' Eliezer, who maintains that a partition is effective in an earthenware oven, what can be said? How is this compatible with the principle that an item is not affected by something not of its type?

רבי אליעזר קל וחומר קאמר.

The Talmud responds: R' Eliezer agrees with this principle. Yet he says that a partition in an earthenware vessel is effective due to his a fortiori inference, which overrides the principle that an item is not affected by something not of its type.

אי הכי, התם נמי לימא קל וחומר: קדשים מחללין קדשים ⁠– חולין לא כל שכן?!

The Talmud challenges: If that is so, that an a fortiori inference overrides this principle, let us say an a fortiori inference there as well, with regard to a sin offering that was slaughtered for the consumption of non-sacred meat: If slaughtering sacrificial animals for the sake of other sacrificial animals desecrates those sacrificial animals, all the more so is it not clear that slaughtering them for the consumption of non-sacred meat desecrates them?