The Torah in Parashat Acharei-Mot (17:13) introduces the mitzva of kisui ha-dam, which requires covering with earth the blood of a bird or a chaya (non-domesticated animal) after slaughtering. The Rama (Y.D. 28:1), based on the Orchot Chayim – cited by the Beit Yosef – rules that although the Torah requires covering the blood after slaughtering, this obligation has no bearing on the validity of the slaughtering. That is to say, if, for whatever reason, the blood of a bird or a chaya was not covered, the meat is nevertheless permissible for consumption, as the slaughtering itself was performed properly. The Beit Yosef writes that the Orchot Chayim drew proof to this position from the Gemara, though he does not specify where in the Gemara this proof appears.
Rav Yom Tov Lipman Heller (author of the Tosfot Yom Tov commentary to the Mishna), in his Divrei Chamudot commentary to the Rosh (Chulin 6:1), suggests that the proof is found in the Gemara’s discussion of kisui ha-dam in contrast to another mitzva performed with earth. In Masekhet Chulin (88b), the Gemara comments that Avraham was rewarded for humbly saying about himself, “I am but earth and ashes” (Bereishit 18:27) by his descendants receiving two mitzvot performed with earth and ash. The ash of the para aduma (red heifer) is used for purification, and the earth of the ground of the Beit Ha-mikdash plays a crucial role in the procedure performed for a sota (suspected adulteress). The Gemara questions why the mitzva of kisui ha-dam – which also involves the earth – was not mentioned as one of the mitzvot given to Avraham’s descendants as a reward, and the Gemara answers that “hana’a leika” – one receives no benefit from kisui ha-dam. Although this is a mitzva which must be fulfilled, it does not provide any actual benefit other than its being a mitzva, and thus it was not mentioned as a reward to Avraham. The Divrei Chamudot comments that if covering the blood was necessary to validate the slaughtering, then the Gemara could not have made such a comment. After all, the mitzva of kisui ha-dam would then provide a very important and valuable benefit – enabling us to eat fowl and non-domesticated animals. Necessarily, then, the Gemara assumed that covering the blood, though obligatory, is not needed to render the meat permissible for consumption, thus providing Talmudic proof to the Orchot Chayim’s ruling.
Rav Shlomo Eiger, in his Gilyon Maharsha to the Shulchan Arukh, refutes this proof. He notes that if the Torah had not commanded the mitzva of kisui ha-dam, then the meat of birds and chayot would, quite obviously, have been permissible for consumption without any need to cover the blood. Hence, the Gemara’s comment could be understood even if the mitzva indeed affects the permissibility of the meat, in that this mitzva would then be adding a further requirement to make such meat permissible for consumption, and it thus does not provide any benefit. This is in contrast to the other two mitzvot mentioned by the Gemara – the ashes of the para aduma and the procedure for a sota – which both serve to solve a halakhic dilemma: the para aduma’s ashes allow for the purification of people and utensils that had become impure, and the procedure for the sota serves to prove the woman’s innocence in order to preserve her marriage. Kisui ha-dam, by contrast, if it were necessary for the meat to be permissible, would be making the process of producing meat more demanding, rather than resolving a problem. As such, it provides no benefit.
Rav Shlomo Eiger therefore points to a different Talmudic source – the Gemara’s discussion earlier (Chulin 84b) regarding the case of a dangerously ill patient who required meat on Shabbat for health reasons, and a bird or chaya was slaughtered on Shabbat for this purpose. Although slaughtering is forbidden on Shabbat, it is allowed when necessary to avoid a possible risk to the life. In such a case, the Gemara concludes, the blood is not covered after slaughtering, because digging is forbidden on Shabbat. (Different views exist as to whether one should cover the blood in such a case if he has loose earth already available – Shulchan Arukh, Y.D. 28:16.) Rav Shlomo Eiger notes that if covering the blood were necessary for the meat to be permissible for consumption, then seemingly, there should be no reason not to cover the blood on Shabbat. After all, just as the prohibition against shechita (slaughtering) is suspended in order to enable the patient to eat, the prohibition against eating without covering the blood would similarly be suspended to enable the patient to eat. Necessarily, then, there is no prohibition against eating without covering the blood.
One might have countered that perhaps there is, indeed, such a prohibition, but nevertheless we allow the ill patient to eat the meat without covering the blood because this is preferable to committing an additional act of Shabbat desecration. Faced with the decision as to whether to violate Shabbat a second time by producing earth for kisui ha-dam, or to allow the gravely ill patient to eat without the blood being covered, one could argue that the latter is preferable, given the unique severity of Shabbat desecration. However, Rav Shlomo Eiger notes the accepted ruling (Shulchan Arukh, O.C. 328:14) that when a dangerously ill patient requires meat on Shabbat, an animal is slaughtered for him even if non-kosher meat is readily available. Several different reasons have been offered for this halakha (see Mishna Berura 328:39), among them the explanation cited by the Beit Yosef from the Ran, that slaughtering on Shabbat is a single forbidden act, whereas eating forbidden meat transgresses a Torah violation with the consumption of each ke-zayit (the volume of an olive). By the same token, Rav Shlomo Eiger writes, were it to be forbidden to eat meat when kisui ha-dam was not performed, Halakha would require digging earth to cover the blood after slaughtering on Shabbat to feed a gravely ill patient. The fact that this is not allowed proves that the failure to perform kisui ha-dam does not affect the status of the meat.