Sanhedrin 73B

משום דהאי לאו אורחיה הוא, והא קא פגים לה. אבל שאר עריות דאורחייהו, ולא נפיש פיגמייהו, אימא לא. כתב רחמנא ״חטא״.

one might say that these two alone are saved at the cost of their respective attackers’ lives, because for this one it is not his natural way, and that one he degrades. But one who rapes one of the other women with whom sex are forbidden, whose natural way is to have sex with a man, and their degradation is not great, one might say that their attackers may not be killed. Therefore, God wrote “sin” to include in this halakha the other women with whom sex are forbidden.

ואי כתב רחמנא ״חטא״, הוה אמינא אפילו חייבי לאוין. כתב רחמנא ״מות״.

And had God wrote only “sin,” I would say that this applies even to women who are forbidden only by a mere prohibition, that they too are to be saved even at the cost of their attackers’ lives. Therefore, God wrote “death,” to teach us that this halakha applies only to transgressions that are punishable by the death penalty.

ואי כתב רחמנא ״מות״, הוה אמינא: חייבי מיתות בית דין ⁠– אין, חייבי כריתות ⁠– לא. כתב רחמנא ״חטא״.

And had God wrote only “death,” I would say that those women who are forbidden to him by a prohibition the violation of which renders him liable to a court-imposed death penalty are indeed to be saved even at the cost of their attackers’ lives, as these are very serious sins, for which they are punished by the court. But those women who are forbidden to him by the type of prohibition the violation of which renders him liable to receive karet, a punishment from God, are not to be saved at the cost of their attackers’ lives. Therefore, God wrote “sin,” to teach that this halakha applies even to prohibitions that are punishable by karet.