שיעורא בעינן ועבודת כוכבים כתותי מכתת שיעורא הכא כל מה דמכתת מעלי לכסוי:
we require a minimum measure in order to fulfill these mitzvot. A shofar must be large enough that, when grasped, part of it protrudes from both sides of one’s hand, and a lulav must be at least four handbreadths long. And since an object of idol worship and its effects must be burned, its size as required for the mitzva is seen by halakha as crushed into powder. Since a shofar or lulav of idol worship is destined for burning, it is considered as if it is already burned, and it therefore lacks the requisite measurement for fulfilling the mitzva. By contrast, here, with regard to the ashes used to perform the mitzva of covering the blood, no minimum measure is required to fulfill the mitzva; in fact, the more the ash is crushed, the better it is for the mitzva of covering the blood.
הדרן עלך כסוי הדם
מתני׳ גיד הנשה נוהג בארץ ובחוצה לארץ בפני הבית ושלא בפני הבית בחולין ובמוקדשין ונוהג בבהמה ובחיה בירך של ימין ובירך של שמאל ואינו נוהג בעוף מפני שאין לו כף
MISHNA: The prohibition of eating the sciatic nerve applies both in Eretz Yisrael and outside of Eretz Yisrael, in the presence of, i.e., the time of, the Temple and not in the presence of the Temple, and with regard to non-sacred animals and with regard to sacrificial animals. And it applies to domesticated animals and to undomesticated animals, to the thigh of the right leg and to the thigh of the left leg. But it does not apply to a bird, due to the fact that the verse makes reference to the sciatic nerve as being “upon the spoon of the thigh” (Genesis 32:33), and a bird has no spoon of the thigh.
ונוהג בשליל ר' יהודה אומר אינו נוהג בשליל וחלבו מותר
And the prohibition applies to a late-term animal fetus [shalil] in the womb. Rabbi Yehuda says: It does not apply to a fetus; and similarly, its fat is permitted.
ואין הטבחין נאמנין על גיד הנשה דברי רבי מאיר וחכמים אומרים נאמנין עליו ועל החלב:
And butchers are not deemed credible to say that the sciatic nerve was removed; this is the statement of Rabbi Meir. And the Rabbis say: They are deemed credible about the sciatic nerve and about the forbidden fat.
גמ׳ מוקדשין פשיטא משום דאקדשיה פקע ליה איסור גיד מיניה
GEMARA: The mishna teaches that the prohibition of eating the sciatic nerve applies to both non-sacred animals and sacrificial animals. The Gemara asks: Is it not obvious that the prohibition applies to sacrificial animals? Would it be reasonable to suggest that because one consecrated it, he has abrogated the prohibition of eating the sciatic nerve from it?
וכי תימא יש בגידין בנותן טעם ואתי איסור מוקדשין וחייל אאיסור גיד האי מוקדשין נוהג בגיד מיבעי ליה אלא קסבר אין בגידין בנותן טעם ובמוקדשין איסור גיד איכא איסור מוקדשין ליכא
And if you would say that sciatic nerves have the ability to impart flavor, i.e., they possess flavor, and the mishna is teaching that the prohibition of eating meat of sacrificial animals comes and takes effect upon the sciatic nerve despite the fact that it is already subject to the prohibition of eating the sciatic nerve, the mishna should have stated: The prohibition of eating meat of sacrificial animals applies to the sciatic nerve. The Gemara suggests: Rather, the tanna of the mishna holds that the sciatic nerve does not have the ability to impart flavor, and the mishna is teaching that with regard to sacrificial animals there is a prohibition of eating the sciatic nerve but there is no additional prohibition of eating the meat of a sacrificial animal.
וסבר תנא דידן אין בגידין בנותן טעם והתנן ירך שנתבשל בה גיד הנשה אם יש בה בנותן טעם הרי זו אסורה
The Gemara challenges this explanation: And does the tanna of our mishna hold that the sciatic nerve does not have the ability to impart flavor? But didn’t we learn in a mishna (96b): In the case of a thigh that was cooked with the sciatic nerve in it, if there is enough of the sciatic nerve in the thigh to impart its flavor to the meat, the entire thigh is forbidden? Consequently, it is clear that the tanna of the mishna holds that the sciatic nerve does possess flavor.
אלא הכא בולדות קדשים עסקינן וקסבר נוהג בשליל וקסבר ולדות קדשים במעי אמן הן קדושים דאיסור גיד ואיסור מוקדשין בהדי הדדי קאתי
Rather, in the mishna here we are dealing with offspring of sacrificial animals. And the tanna holds that the prohibition of eating the sciatic nerve applies with regard to a fetus, and he also holds that the offspring of sacrificial animals are consecrated even while they are in the womb of their mother. Consequently, the prohibition of eating the sciatic nerve and the prohibition of eating sacrificial animals come into effect at the same time, and therefore both prohibitions apply and one does not say that a prohibition does not take effect where another prohibition already exists.
ומי מצית מוקמת לה בשליל והא מדקתני סיפא נוהג בשליל מכלל דרישא לאו בשליל עסקינן הכי קאמר דבר זה מחלוקת דרבי יהודה ורבנן
The Gemara challenges this explanation: Can you interpret this clause of the mishna as referring to a fetus? From the fact that the latter clause teaches: It applies to a late-term fetus, and Rabbi Yehuda holds that it does not apply to a late-term fetus, it may be inferred that in the first clause we are not dealing with a fetus. The Gemara explains: This is what the tanna of the mishna is saying: This matter that was taught in the first clause is a matter of dispute between Rabbi Yehuda and the Rabbis.
ומי מצית אמרת דתרוייהו בהדי הדדי קאתו והתנן על אלו טומאות הנזיר מגלח על המת ועל כזית מן המת
The Gemara again challenges the explanation that the first clause of the mishna is referring to a fetus: And how can you say that both prohibitions come into effect at the same time? But didn’t we learn in a mishna (Nazir 49b): A nazirite shaves for having become impure from these sources of ritual impurity: For impurity imparted by a corpse and for impurity imparted by an olive-bulk of a corpse.
וקשיא לן על כזית מן המת מגלח על כולו לא כל שכן ואמר רבי יוחנן לא נצרכה אלא לנפל שלא נקשרו אבריו בגידין
And the clause: For impurity imparted by a corpse, is difficult for us, as it seems unnecessary; if a nazirite must shave for impurity imparted by an olive-bulk of a corpse, is it not all the more so true that he must shave for impurity imparted by an entire corpse? And Rabbi Yoḥanan says: It is necessary only for a miscarried human fetus whose limbs had not yet become joined to its sinews. Since the spine is complete the fetus is considered a full corpse, but as the limbs have not yet joined to the sinews it does not contain an olive-bulk of flesh.