The Torah in Parashat Emor (23:27-32) introduces a series of commands relevant to the 10th of Tishri – the day of Yom Kippur. These include the command to offer a special series of sacrifices (“Ve’hikrabtem Isheh L’Hashem” – 23:27), referring to the Musaf offering, which the Torah describes in Parashat Pinhas (Bamidbar 29:7-11). The Musaf offering on Yom Kippur consists of one bull, one ram and seven sheep as an Ola (burnt-offering), and a goat as a Hatat (sin-offering).
Additionally, the Torah issues a command forbidding performing Melacha (constructive work) on Yom Kippur (23:28), and a command forbidding eating and drinking on this day (23:29). Finally, the Torah adds an affirmative command requiring that we observe Yom Kippur as a “Shabbat Shabbaton” – a day of cessation of work (23:32). Thus, refraining from work is required on Yom Kippur by force of both an affirmative command and a prohibition against performing work.
The Sefer Ha’hinuch writes that the Torah forbade performing work on Yom Kippur so that we will be able to fully devote our attention to pleading for forgiveness for our wrongdoing. If we would be permitted to work, we would be preoccupied with our workday responsibilities, and would thus not focus on prayer and repentance as we should on this day.
All work which is forbidden on Shabbat is forbidden also on Yom Kippur. The only exception is what the Gemara calls “Kenibat Ha’yarak,” which refers to either cutting vegetables, or separating the edible parts of the vegetables from the inedible parts. This is permitted on Yom Kippur afternoon, from the time for Minha, whereas this is forbidden on Shabbat Mi’de’rabbanan (by force of Rabbinic enactment). Nevertheless, the Sefer Ha’hinuch observes, it has become customary to refrain from “Kenibat Ha’yarak” even on the afternoon of Yom Kippur.
Another difference between Shabbat and Yom Kippur in this regard is that performing Melacha on Shabbat is punishable by the most severe form of capital punishment – Sekila (stoning) – whereas performing Melacha on Yom Kippur is punishable by Karet. Surprisingly, this distinction is noted by the Shulhan Aruch (Orah Haim 611) – despite the fact that, seemingly, this point has no practical Halachic implications nowadays. The Shulhan Aruch presents only the practical information relevant for the observance of Halacha in our time, and the question thus arises as to why Maran, the author of the Shulhan Aruch, found it necessary to note the different punishments for these violations. The commentators explain that this point is relevant to the case of one who caused his fellow damage on Shabbat or Yom Kippur in a manner which involved performing a Melacha. The principle of “Kim Leh Be’de’rabba Mineh” establishes that if one performs an act which simultaneously transgresses two prohibitions, he receives only the punishment for the more severe violation, and is exempt from punishment for the lesser violation. However, this is applicable only if the more severe punishment is one administered by the courts – as opposed to Karet, which is delivered only by G-d. Thus, if one damages his friend on Shabbat in a manner which entails Shabbat desecration, he will not be required to compensate his friend for the damage, because this act renders him liable to the severe punishment of Sekila. If, however, this happened on Yom Kippur, he would be liable to pay for the damages, because the punishment of Karet for desecrating Yom Kippur does not absolve him from responsibility for the damages.
The prohibition against performing Melacha on Yom Kippur applies in all times and places, and to both men and women.