שמות, פרק י״ב, פסוק כ׳

A grand and comprehensive conclusion seals the laws of Passover, summarizing the festival's two essential requirements: the absolute ban on leaven and the strict obligation to eat unleavened bread [קאסוטו]. Following a detailed list of punishments for violations, the topic wraps up with a direct and clear warning [אבן עזרא]. The prohibition covers anything containing leavening agents [רש״י, ביאור שטיינזלץ]. However, the ban is intentionally broad, extending beyond pure, fully leavened bread to include any mixture containing even a small trace of leaven, such as beer or fermented sauces [רש״י, תורה תמימה]. This wide inclusion is compared to a king who orders the expulsion of every doctor from his city; the decree applies not only to expert physicians but to anyone with even a little medical knowledge [הכתב והקבלה, רלב״ג]. Despite this broad net, there is a distinction in the level of punishment. While eating pure leaven carries the severe punishment of being cut off, consuming a mixture containing leaven, though strictly forbidden by the Torah, does not result in the same harsh penalty [רמב״ן, העמק דבר, תורה תמימה].

On the other side of the command, eating unleavened bread is not merely an option but an absolute obligation [אבן עזרא]. This duty is entirely independent of the Passover sacrifice. It applies in all places, including outside the Land of Israel where sacrifices cannot be offered, and remains in effect throughout history, even when the Temple does not stand [רשב״ם, רלב״ג, חזקוני, ביאור יש״ר]. Furthermore, the requirement that the unleavened bread be eaten in all dwellings defines the specific type of bread required. It must be a common bread suitable for consumption anywhere. This rule excludes holy breads that can only be eaten in Jerusalem, such as thanksgiving loaves, the showbread, and first fruits [רש״י, רלב״ג, מלבי״ם]. The command embraces various types of unleavened bread, including those made from fine flour or special portions reserved for priests. However, because the Torah elsewhere defines this food as the "bread of affliction," wealthy or enriched breads are disqualified. Therefore, dough that is boiled, sponge cakes, or baked goods kneaded with rich ingredients like oil and honey cannot be used to fulfill the obligation [תורה תמימה, מלבי״ם].