This chapter dealt primarily with the halakhot concerning the mitzva of covering the blood of a slaughtered undomesticated animal or bird, based on careful analysis of the relevant verse (Leviticus 17:13). The mitzva to cover the blood applies both within Eretz Yisrael and outside it, and is in effect independent of the existence of the Temple. As stated in the Torah, the mitzva of covering the blood applies only to the blood of birds and undomesticated animals. Additionally, only non-sacred animals or birds are included in the mitzva, either because it is impossible to properly cover the blood upon the altar or due to the fact that the verse limits the mitzva to undomesticated animals, which cannot be brought as offerings. An undomesticated animal and a bird are counted together as one unit with regard to the mitzva of covering their blood. That is to say, if one slaughtered both an undomesticated animal and a bird, he may cover all the blood together, just as he would cover the blood of multiple undomesticated animals together. Although the verse mentions the obligation to cover the blood in a case where one traps the animal or bird, the Gemara derives that the obligation applies even in a case where one slaughters undomesticated animals or birds that were not trapped. Nevertheless, the Sages interpreted the verse as an injunction with regard to the proper consumption of meat, i.e., meat should be consumed only after one exerts himself to obtain the animal, and meat should not be readily available in one’s home. The mention of this halakha leads to a further digression in which the Gemara discusses financial management and suggests the proper manner in which one should support his family. The mitzva of covering the blood applies only to the blood that was spilled due to slaughter, not to blood that was spilled due to another form of killing. Additionally, the mitzva applies only in the case of an act of slaughter that permits the meat for consumption. If one slaughtered an undomesticated animal or a bird and found it to be a tereifa, or if one slaughtered an undomesticated animal or a bird for the purpose of idol-worship, one is not required to cover the blood. The early commentaries explain that the mitzva of covering the blood is part of the mitzva of ritual slaughter and is therefore applicable only if the slaughter itself is valid. The mitzva of covering the blood is primarily incumbent upon the one slaughtering the animal. If he did not cover the blood, the obligation falls upon any bystander who notices the uncovered blood. Due to this discussion, the Gemara briefly discusses an individual’s rights with regard to the performance of a mitzva and the penalty incurred by one who prevents another from performing that mitzva. If, after properly covering the blood, it subsequently becomes uncovered, one is exempt from covering the blood a second time. But if the blood was initially covered by earth blown by the wind, although one is not required to cover the blood so long as it remains covered, should the blood become uncovered he must cover it. This is in accordance with the principle that there is no rejection with regard to mitzvot. With regard to the question of which blood must be covered, the Gemara concluded that the obligation is to cover the blood of the soul, which includes blood that spurts from the area where the slaughter is performed as well as blood remaining on the slaughtering knife. One is not required to cover all the blood. In cases where the blood became mixed with water or another liquid, if the mixture is such that it still maintains the appearance of blood, one is obligated to cover the mixture. In light of this halakha, the Gemara also discusses the characteristics necessary to define a liquid as blood, as well as the status of blood plasma. The Gemara concludes that if the plasma maintains a reddish hue, it is considered actual blood with all the halakhic ramifications. With regard to the manner of covering the blood, the Gemara concludes that one must cover the blood from above and below, and that simply covering it from above is insufficient. One should cover the blood using his hand or the slaughtering knife, but not with his foot, so that the mitzva will not become contemptible to him. The Gemara also concludes that the verse does not require specifically the use of earth to cover the blood. Rather, one may use any substance that, like earth, is finely crushed and allows for the growth of plants inside it. One may not cover the blood with a vessel, nor may he use thick substances. Also, any powder produced from ground metals may not be used for the mitzva except that produced from ground gold, to which the Gemara attributes a unique status. Unlike some mitzvot, with regard to which one may not perform them using a substance from which he is prohibited to derive benefit, with regard to the mitzva of covering the blood, he is permitted to cover it with a substance from which he is prohibited to derive benefit. This is in accordance with the principle that mitzvot were not given for benefit; rather, their performance is meant solely to fulfill a divine decree. These were the primary topics discussed in the chapter. Other topics were discussed tangentially, e.g., the halakha of an ineffective slaughter, aggadic accounts and lessons with regard to one’s income, and the mitzvot gained in the merit of our forefather Abraham.

Therefore the children of Israel eat not the sciatic nerve that is upon the spoon of the thigh, until this day; because he touched the hollow of Jacob’s thigh, on the sciatic nerve. (Genesis 32:33)

This verse teaches the prohibition of eating the sciatic nerve. Yet, unlike almost all other mitzvot written in the Torah, this prohibition is not stated clearly as an instruction to Moses but is mentioned in the context of events that occurred long before the Torah was given on Mount Sinai. For this reason, there are many practical questions that arise about this topic. Some of the questions raised in this chapter with regard to the prohibition of eating the sciatic nerve include: Does this prohibition apply with regard to all living creatures or only to some of them? Does it apply to non-kosher species of animals? Does it apply to the nerve in only one thigh or to the nerves in both thighs? Does this prohibition apply with regard to consecrated animals? Does it apply only in Eretz Yisrael or also in the Diaspora? Although the verse specifies that a nerve in the thigh is forbidden, it is not clear from the verse precisely which nerve it is. The Gemara therefore seeks to clarify exactly which nerve this is and whether the entire length of the nerve is forbidden or just a part of it. The Gemara also discusses the practicalities of removing this nerve from the thigh. How must it be removed? Is it just the nerve that must be removed, or must one remove some of the surrounding flesh? Another type of practical issue that is discussed in this chapter pertains to interactions between Jews and gentiles. In a location where all animals are slaughtered only by Jews, and the butchers publicize when they sell a tereifa to a gentile, a Jew may purchase raw meat from a gentile. The Gemara explores whether in such a case a Jew may send a whole animal thigh to a gentile as a gift, or whether he must be concerned that the gentile may then sell it to a Jew without removing the sciatic nerve. Other issues discussed include whether the sciatic nerve has the status of meat or whether it is considered inedible. This question has important ramifications with regard to principles governing mixtures of forbidden and permitted substances, as well as whether the sciatic nerve imparts forbidden flavor to the thigh if it is not removed before the thigh is cooked. These questions and related topics form the basis of the material discussed in this chapter.