Leviticus 23:27-28

²⁷Also on the tenth day of this seventh month is a day of atonement: it shall be a holy convocation to you; and ye shall humble your souls, and offer a whole-burnt-offering to the Lord.

²⁸Ye shall do no work on this self-same day: for this is a day of atonement for you, to make atonement for you before the Lord your God.