Leviticus 16:29-31

And it shall be a statute for ever unto you: in the seventh month, on the tenth day of the month, ye shall afflict your souls, and shall do no manner of work, the home-born, or the stranger that sojourneth among you: for on this day shall atonement be made for you, to cleanse you; from all your sins shall ye be clean before Jehovah. It is a sabbath of solemn rest unto you, and ye shall afflict your souls; it is a statute for ever.