Today’s daf continues the discussion of shi’urim – the amount necessary to be held liable for eating on Yom Kippur. Rabbi Yohanan is quoted by the Gemara as saying that shi’urim and onashim – both the amount that is considered significant and the punishment that will be meted out on the individual who eats forbidden foods according to those measurements – are halakha le-Moshe mi-Sinai, they are traditions handed down from Moses on Mount Sinai, which have the weight and significance of Biblical law. In response to the question raised that the onashim are clearly written in the Torah, the Gemara explains that Rabbi Yohanan was teaching that the shi’urim upon which the onashim are based (for without a standard minimum measurement, how could we know when the punishments are appropriate?) are halakha le-Moshe mi-Sinai.
A baraita that is brought in support of this understanding of Rabbi Yohanan adds another opinion, as well. According to Aherim they were established – or, more correctly, were forgotten and reestablished – by the court of Jabez. Rashi identifies Jabez as Otni’el ben Kenaz, based on a Rabbinic tradition. The name appears in I Divrei ha-Yamim 2:55 and 4:9-10 as one of the descendants of Yehuda, and from the context it appears that he was one of the Jewish leaders of his time. He is identified as the head of one of the “the families of soferim (scribes) who lived in Yaabetz [Jabez]” so it appears that he was head of the soferim – the Sages in his generation.
The rules of shi’urim notwithstanding, there are times when a person can eat more than a shi’ur, yet still not transgress the prohibition of eating forbidden foods.
Reish Lakish said: One who eats in an excessive manner on Yom Kippur, to the degree that he forces himself to continue eating even when full is exempt, e.g., one who ate beyond being satiated on Yom Kippur eve and then ate something else as soon as the fast began. What is the reason for that? Because the Torah does not mention the prohibition of eating on Yom Kippur, but it was written “any soul which shall not be afflicted in that same day, he shall be cut off from his people” (Vayikra 23:29), excluding one who harms himself, e.g., one who does not enjoy his food at all.
The Tosafot Yeshanim point out that there are different levels of akhila gasa. One level is overeating – when a person is full and continues to eat. Reish Lakish is referring to a different level, when a person continues eating to the extent that he finds the food disgusting. Someone who does damage to himself by way of eating has not transgressed this prohibition.