990. Forms of Yom Kippur "Affliction"

Shvisas Asor 1:4

There is a positive mitzvah to refrain from eating and drinking on Yom Kippur, as per Leviticus 16:29, “You shall afflict yourselves.” According to our oral tradition, the definition of afflicting one's self is fasting. Whoever fasts on Yom Kippur fulfills this obligation, while one who eats or drinks both fails to fulfill the obligation and violates a prohibition, as per Leviticus 23:29, “Whoever does not afflict himself will be cut off.” From the fact that the Torah punishes one who does not fast with kareis, we can infer that doing so on Yom Kippur is prohibited. One who eats or drinks accidentally on Yom Kippur must bring a sin offering of fixed value.

Shvisas Asor 1:5

The oral tradition also teaches that it is prohibited to wash, anoint, wear leather shoes or engage in marital relations on Yom Kippur. It is a positive mitzvah to refrain from these things the same way it is to refrain from eating and drinking. This is extrapolated from the phrase, “a Sabbath of Sabbaths.” “A Sabbath” refers to refraining from eating. “Of Sabbaths” comes to include these other activities. One is only liable to kareis or a sin offering for eating or drinking on Yom Kippur. If one washes, anoints, wears leather shoes or engages in marital relations, he receives the lashes giving for acting rebelliously.