Yom Kippurim (literally the Day of Atonement) is commemorated from the ninth day of the seventh month in the evening until the tenth day of the seventh month in the evening (Leviticus 23, 26-32).
Yom Kippurim is described as Shabbat Shabbaton in an emphatic command to rest and refrain from work (Leviticus 23, 28; 23, 32).