The final sugya in Avodah Zarah discusses kashering a knife.
This passage teaches how one kashers a knife. It seems that by plunging it in untilled soil, one will remove the outer layer that has been in contact with the forbidden substance.
The knife that has been kashered can only be used with cold food. Using it with hot food would cause it to emit the taste that it absorbed from the prohibited food.
In this fascinating story, the Persian King Shappur cuts some etrog slices and gives it Bati b. Tobi without kashering his knife, but kashers the knife before he gives it to Mar Yehudah. Bati is not too happy that he is not being treated like a non-Jew. The king responds that he does not know if Bati b. Tobi really is observant. And in a highly humorous end to the masekhet, the king says to him, “I remember what you did last night.” Too bad we’ll never know what naught Bati did last night. And come on, can you think of a better way to end Masechet Avodah Zarah then with a non-Jewish king kashering a knife and telling another Jew he is not observant enough?
That’s it folks. We finished another masekhet, another wild ride through the complicated, topsy-turvy, free-thinking, beautiful minds of Hazal, our rabbis of blessed memory. I’m hoping you found this Tractate as fascinating as I did. Discussions about how Jews can preserve their identity in a world full of people whose identity they do not share. When can Jews trust non-Jews, and when can they not? When can they use their things, and when can they not? What foods of theirs can they eat and what can they drink (not wine, that’s for sure)? It was a relevant tractate then and much of it is still relevant now. I hope you have time to review some of your learning and most importantly, I hope you continue with us onto our fifth masekhet—Kiddushin!