The Mishnah and Talmud tractate mainly concerned with the laws of Yom Kippur is Yoma.
Yoma is the fifth tractate in Seder Moed, the Mishnah’s Order of Festivals. Its name is Aramaic for “the day,” an abbreviated reference to Yom Kippur. The tractate contains eight chapters and discusses both the ancient Temple service and the rules governing observance after the Temple’s destruction.
Its central sections describe the High Priest’s preparation, the order of sacrifices, the lottery of the two goats, the incense offering, and the rare entry into the Holy of Holies. These passages preserve a detailed rabbinic account of a ritual that could no longer be performed after the Second Temple was destroyed in 70 CE.
The final chapter turns to practices that remain relevant without a Temple, including Yom Kippur’s five traditional afflictions: fasting, avoiding bathing, avoiding anointing, refraining from leather footwear, and abstaining from marital relations. It also discusses repentance and when atonement applies. Berakhot concerns blessings and prayers, Megillah focuses chiefly on Purim, and Sukkah concerns the festival of Sukkot.