Leviticus 23:26-28 (TLV)
Adonai spoke to Moses, saying: “However, the tenth day of this seventh month is Yom Kippur,[f] a holy convocation to you, so you are to afflict yourselves. You are to bring an offering made by fire to Adonai. You are not to do any kind of work on that set day, for it is Yom Kippur, to make atonement for you before Adonai your God.
Day of Atonement