Do Not Eat Chametz Mixtures on Passover
Nothing Leavened — The Zero-Tolerance Standard
Exodus 12:20: “You shall eat nothing leavened (kol machmetset); in all your dwelling places you shall eat unleavened bread.” The word “kol” (all, anything) signals comprehensiveness: not just bread, not just obvious chametz, but anything leavened in any form. The rabbis read this as closing the gaps in the earlier chametz prohibitions — where those covered chametz in its primary form (bread, se’or), this verse covers chametz mixtures: foods in which chametz is present as a component, even in a relatively small amount. The result is a Passover prohibition that admits no leniency through dilution or mixture.
The phrase “in all your dwelling places” appears here as it did in the se’or prohibition (#473) — extending the scope beyond the primary residence to every location the Israelite inhabits or controls. The verse’s comprehensiveness works on two axes: every form of chametz (not just bread, but mixtures) and every location (not just the main home, but all dwellings). Together these two axes create the most complete possible prohibition: no chametz, in any form, anywhere.
Chametz B’Masheh’u — The Unique Stringency
The principle “chametz b’masheh’u” (chametz in any amount) is one of the most distinctive features of Passover halacha. The normal rule of bitul (nullification) — by which a forbidden substance that falls into a permitted food in less than a 1:60 ratio is considered nullified — does not apply to chametz on Passover. A drop of beer in a pot of soup renders the entire soup forbidden. A trace of wheat flour in a sauce renders the sauce forbidden. No ratio, no matter how small, removes the prohibition.
The reasoning, as developed by the rishonim, runs as follows: bitul applies to substances that cannot practically be recovered. Chametz before Passover can be identified and removed; the failure to do so is a failure of the person, not an unavoidable mixing. The Torah’s zero-tolerance standard at Exodus 12:20 reflects that chametz is uniquely an avoidable contamination — if you inspected properly, burned the chametz you found, sold the chametz you couldn’t burn, and nullified the remainder, no chametz should be present in your food. The presence of chametz in a mixture means the preparation was incomplete.
Passover Label Reading — The Contemporary Application
The chametz mixture prohibition is what drives the intensive Passover label-reading and product-certification practice of observant Jewish communities. Processed foods contain innumerable additives, starches, and flavorings — any of which might derive from the five grains. A product might contain wheat starch in an ingredient seven layers deep. Because chametz in any amount renders the entire product forbidden on Passover, and because the normal nullification rule does not apply, the verification of chametz-free status requires either a full ingredient audit or a reliable certification (“Kosher l’Pesach” certification) by a rabbinical authority who has verified the production process.
The comprehensive nature of the Passover chametz prohibition — reaching every form of chametz in every mixture at every location — creates one of the most extensive annual reorganizations of domestic life in any religious tradition. The six weeks before Passover that observant households spend preparing — cleaning, checking, replacing, certifying — are the direct practical consequence of the absolute standard that Exodus 12:20 establishes: nothing leavened, anywhere, in any amount.
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