Minute Prohibited Substances

Since we say that everyone agrees that something that is prohibited in even the smallest amount [isur de-mashehu] is forbidden “in the first instance” whether or not it is mixed with a substance of its own type, we must inquire about those people who are unwilling to be thorough in the extraction of [forbidden substances from] meat and leave behind a tiny amount of forbidden fat or sciatic nerve and then cook that meat in their pots. Do we say that since we know that if such people were aware, they would not cook forbidden fat in their pots, so this is considered “after the fact” [i.e., it is not a case “in the first instance,” when the prohibited substance is forbidden in any amount, but “after the fact,” when it is not forbidden in any amount]? Or perhaps we should apply the general principle that “one may not act with familiarity toward heaven” [see, e.g., b. Berakhot 34a]—because we know that it is due to their laziness, as they do not want to learn how to extract forbidden substances from meat according to the established rules of law, so one who buys the meat is relying on an ignorant person who is not precise in his preparation and thus consuming something that is prohibited in any amount in the first instance?

For it is certainly a well-known law that anything that is presumed to be prohibited may not be eaten by a Jew until he knows how it was rendered kosher. Thus the Gemara [b. Beẓah 25a] states that while an animal is alive, it is presumed to be prohibited, and it remains that way until it becomes known to you how it was slaughtered, that is, until you find out exactly how it was slaughtered. Similarly, any animal thigh is presumed to contain forbidden fat and sciatic nerve until you find out who rendered that thigh kosher. It is all the more so prohibited to eat meat that comes from someone whom we know does not know how to extract prohibited substances properly. Regarding any person known to be imprecise in these matters, if we [actually] find forbidden fat in meat that comes from him, we must remove him from his post, even if forbidden fat the size of a grain of barley is discovered in [only] one spot. We are required to separate ourselves from him and his [improper] extractions.

If anyone does not want to separate from him, but declares, “Whoever wishes to extract after him is welcome to do so. I will not examine what he has done, and I will eat from whatever he has prepared,” certainly if even a minimal amount of prohibited substance remains, this is considered “in the first instance,” and it is prohibited to eat any food in which that minimal forbidden substance was cooked. For undoubtedly all Jews must be scrupulous and find out precisely how an item that was once presumed to be prohibited was rendered kosher, as stated above: until it becomes known to you how it was slaughtered.

If we know someone is not precise in his preparation, whoever eats of his meat will be consuming something that is prohibited in any amount in the first instance, and we maintain that one may not eat such a thing because one may not nullify a prohibited substance in the first instance. Since it may not be nullified, if someone mixes a minimal amount of forbidden fat, or blood, in the first instance, whether with a permitted substance of its own type or not, it renders all the food forbidden. Furthermore, since the food is forbidden, the pot is likewise forbidden, and one may not use any of their vessels for cooking, because they do not examine scrupulously whether all forbidden substances have been fully extracted from the meat they eat. All the more so, such vessels are forbidden if they belong to those who question the need for extraction of forbidden substances from meat, arguing that the fat which is in the thigh is not prohibited by the Torah, for they are committing a grave error, as it is certainly forbidden by biblical law. [ . . . ] It is a well-known law that the fat of the sciatic nerve is prohibited and therefore one must scrape around it to remove its fat, and, as with other forbidden fat, one must examine carefully to ensure it has been extracted. One should not listen to anyone who is lenient regarding the fat of the sciatic nerve; his statements should be considered as bordering on heresy.

Consequently, it is inevitable that anyone who doubts this matter and is not scrupulous in the extraction of forbidden substances from meat will leave behind a minimal amount of forbidden fat, which means that they will eat something which is prohibited in any amount in the first instance, and therefore all their vessels are forbidden.

If you say that since they do not know it is a biblical requirement to extract fully all forbidden substances from the thigh, they should therefore be considered unwitting sinners, I reply that they are willful, purposeful sinners. They should have learned from a local God-fearing scholar who accepts the opinion of the sages how to be scrupulous in these matters. Since they failed to learn proper conduct, they are considered willful sinners. [ . . . ] Thus, all those who question this matter without justification are intentional transgressors, and likewise all who are lenient because they do not want to go to the bother of learning—since it is an effort for them to render food properly kosher—they are certainly willful sinners as well.

Accordingly, all Jews must be scrupulous and eat only appropriate foods, and one who does not follow this practice is an intentional transgressor. In addition, one should keep away from people who have not learned what to do and also from their vessels, as they eat substances which are prohibited in any amount in the first instance.