Levítico 23:29 Halacá: Mishneh Torah, Rest, Gray Matter III, The Sabbath Epistle & Mishneh Torah, Negative Mitzvot

Another positive command concerning Yom Kippur requires us to abstain from eating or drinking on that day, as it is written: "You shall afflict yourselves" (Leviticus 16:29). According to tradition, self-affliction signifies fasting. Whoever fasts on Yom Kippur fulfills a positive command, and whoever eats or drinks on it breaks a positive command and transgresses a negative command, as it is written: "Whoever will not abstain and fast on that day shall be cut off" (Leviticus 23:29). Since the verse [explicitly] punished one who did not afflict himself [with] the punishment of excision, we have [also] learned that we are warned about eating and drinking on it. And anyone who eats or drinks on it inadvertently must bring a fixed sin-offering.

[If] one ate foods that are not fitting for human consumption, such as bitter grasses or foul syrups; or drank liquids that are not fitting for human drinking, such as [fish-]broth, fish oil or undiluted vinegar, he is exempt from excision — even [if] he ate or drank a lot. However he receives lashes for rebellion.

The Torah (Vayikra 23:29) teaches that one who eats on Yom Kippur is punished with kareit (spiritual excision).¹Rashi (Vayikra 17:9 s.v. V’nichrat and 20:20 s.v. Aririm) mentions that kareit can entail dying childless, burying one’s children, or dying prematurely. The Gemara (Mo’eid Katan 28a) defines “prematurely” as before age fifty. This punishment takes effect, according to the Mishnah (Yoma 8:2), only if he eats or drinks the shiur (requisite amount), which, for Yom Kippur, is a volume of food equivalent to the size of a large date (kakotevet hagasah) or a quantity of liquid that could fill one’s cheek (melo lugmav).