וְאִ֗ישׁ אֲשֶׁ֨ר יִקַּ֧ח אֶת־אִשָּׁ֛ה וְאֶת־אִמָּ֖הּ זִמָּ֣ה הִ֑וא בָּאֵ֞שׁ יִשְׂרְפ֤וּ אֹתוֹ֙ וְאֶתְהֶ֔ן וְלֹא־תִהְיֶ֥ה זִמָּ֖ה בְּתוֹכְכֶֽם׃
Y el que tomare mujer y a la madre de ella, comete vileza: <span class="x" onmousemove="Show('perush','Este es el <b>228vo Precepto Positivo</b> enumerado por el Rambam en el Prefacio a Mishné Torá, su “Compendio de la Ley Hebrea” para todo el Pueblo de Israel.',event);" onmouseout="Close();">quemarán en fuego a él y a ellas</span>, porque no haya vileza entre vosotros.
Shenei Luchot HaBerit
באש ישרופו אותו ואתהן . When someone marries a wife [mother-in-law. Ed.] and her mother (20,14), the Torah decrees death by "burning" for all three parties. Our sages teach us the type of "burning" the Torah has in mind for this transgression as well as for all other instances where death by "burning" is decreed. It is similar to what happened to Nadav and Avihu whose souls were burned while their bodies remained lifeless but intact. If the Torah would have written ישרפו באש, the fire would have first consumed the body as is the case when someone is "burned at the stake" Since the Torah mentions the word אש first, it is clear that a different kind of burning is meant.