Leviticus 23:26-28

And the Lord said to Moses, Also the tenth day of this seventh month is the Day of Atonement; it shall be a holy [called] assembly, and you shall afflict yourselves [by fasting in penitence and humility] and present an offering made by fire to the Lord. And you shall do no work on this day, for it is the Day of Atonement, to make atonement for you before the Lord your God.