Leviticus 23:23-27

And the LORD spake unto Moses, saying, Speak unto the children of Israel, saying, In the seventh month, in the first day of the month, shall ye have a sabbath, a memorial of blowing of trumpets, an holy convocation. Ye shall do no servile work therein: but ye shall offer an offering made by fire unto the LORD. And the LORD spake unto Moses, saying, Also on the tenth day of this seventh month there shall be a day of atonement: it shall be an holy convocation unto you; and ye shall afflict your souls, and offer an offering made by fire unto the LORD.