Chullin 8 - Hot Knife

Rabbi Zeira said in the name of Shmuel, "If someone made a knife white-hot and slaughtered with it, his slaughter is valid, since the knife first cuts and then later burns, and thus the shechitah happens because of the sharpness of the knife, not because of its heat."

One is allowed to slaughter with the knife of idolatry, because he damages the animal by killing it, and does not derive benefit, but he is not allowed to cut the meat with this knife, because this improves it.

However, the forbidden fat collected on the knife of idolatry surely makes the meat non-kosher!? Rav agrees and says that one must peel away some meat at the place of incision, and Rabbah bar bar Channah says that one needs only wash the meat. What is the argument? Rav considers the place of the incision hot enough to absorb the forbidden fat. Alternatively, both consider it hot, but Rabbah says that the pipes are busy expelling the blood and do not absorb fat. Or perhaps both consider the place of incision cold, yet Rav says that it absorbs the forbidden fat because of the pressure exerted by the knife.

Art: Francis Wheatley - Knives, Scissors and Razors to Grind