Rabbi Yehudah argues that the Torah's command to "eliminate leaven from your houses" means one specific thing: you must burn it. Not scatter it, not crumble it into the wind, not toss it into a river. Burn it.
His reasoning follows a careful analogy. Consider nothar, the leftover portions of the Paschal lamb that were not consumed by morning. The Torah forbids eating nothar, just as it forbids eating chametz during Passover. And the established rule for nothar is that it must be destroyed specifically by fire (Exodus 29:34). Since both chametz and nothar share the same prohibition against eating, Rabbi Yehudah reasons that they should share the same method of destruction.
But the Mekhilta immediately challenges this logic. What about neveilah — the carcass of an animal that died without proper slaughter? Eating neveilah is also forbidden, yet no one requires it to be burned. It can be disposed of in any manner. If the prohibition against eating does not automatically require burning in that case, why should it require burning for chametz?
The objection forces a deeper question: what makes chametz more like nothar than like neveilah? The debate that follows explores whether the severity of the punishment — specifically kareth, the divine penalty of being "cut off" — is the distinguishing factor. This is rabbinic law at its most rigorous, testing every analogy against counterexamples.