שמות, פרק י״ב, פסוק י״ט

The festival of freedom introduces a dietary restriction that fundamentally transforms the physical space and legal reality of the home. The absolute removal of all leavening agents serves as a critical step in forging the new identity of a nation leaving Egypt. Although the festival spans a specific seven-day period, the actual elimination of the leaven must be completed before the holiday even begins, ensuring the entire week remains absolutely pristine [חזקוני].

The prohibition targets two distinct categories to leave no room for loopholes. One is the sourdough starter, an intensely fermented dough acting as yeast. While not eaten on its own, it possesses the power to cause other dough to rise [אבן עזרא, שפתי חכמים, שטיינזלץ]. The other category encompasses any regular leavened food, extending even to mixtures that merely carry a distinct leavened taste [אבן עזרא, רש״ר הירש]. Both are explicitly forbidden and carry the same severe penalty of spiritual excision. If only regular leavened food were prohibited, one might assume the inedible sourdough starter was permitted. Conversely, if only the powerful sourdough starter were banned, one might think ordinary leavened bread was exempt. Addressing both clarifies that consuming either results in the identical severe punishment [רש״י, בכור שור, שפתי חכמים].

Because the consequence for eating leaven is so grave, merely nullifying it in one's mind is insufficient. The strict requirement to physically remove and destroy it from the home acts as a necessary protective barrier. It ensures that no one accidentally eats leaven out of sheer year-round habit [הכתב והקבלה, העמק דבר, תיבת גמא]. The requirement that leaven not be found also hints at the traditional practice of actively searching the home by candlelight, as focused searching naturally leads to finding [תורה תמימה].

The demand to clear the home establishes the physical and legal boundaries of this prohibition. The primary approach among commentators [רש״י, מזרחי, דברי דוד] explains that comparing a home to a geographic border establishes a legal principle of ownership. Just as a home is under a person's complete control, the prohibition applies exclusively to leaven under their legal responsibility. Consequently, leaven owned by a non-Jew that happens to be on an Israelite's property is not forbidden, provided the Israelite has not assumed financial responsibility or guardianship over it. Conversely, [רמב״ן] argues that a home and a border are fundamentally the same, as both represent a person's domain. According to this view, the exemption for a non-Jew's leaven is derived from a different legal nuance of ownership. Instead, the focus on the home introduces a specific leniency. An Israelite does not violate the core prohibition if they deposit their own leaven in a non-Jew's home, because the violation only occurs when the leaven is both owned by the Israelite and physically located within their own domain [רמב״ן, רלב״ג]. Other perspectives bridge these views by further refining the exact definitions of property and financial liability [העמק דבר, גור אריה].

Finally, the law applies equally to the native resident and the convert. A native refers to a permanent, deeply rooted citizen, conceptually likened to the steady, visible rising of the sun. In contrast, a convert is someone who has wandered and settled in a new place [אבן עזרא, ביאור יש״ר]. Because the historical miracles of the Exodus were performed specifically for the Israelites of that era, one might mistakenly assume that a newer convert is exempt from the strict prohibition and its corresponding penalty. They are explicitly included to dispel this notion [רש״י, אבן עזרא]. This absolute inclusion in the prohibition against eating leaven is particularly striking given that a convert is completely restricted from partaking in the Passover sacrifice itself until they have undergone circumcision [קאסוטו].