Leviticus 23:23-23:32
The Lord spoke to Moses, saying: Speak to the Israelite people thus: In the seventh month, on the first day of the month, you shall observe complete rest, a sacred occasion commemorated with loud blasts. You shall not work at your occupations; and you shall bring an offering by fire to the Lord.
The Lord spoke to Moses, saying: Mark, the tenth day of this seventh month is the Day of Atonement. It shall be a sacred occasion for you: you shall practice self-denial, and you shall bring an offering by fire to the Lord; you shall do no work throughout that day. For it is a Day of Atonement, on which expiation is made on your behalf before the Lord your God.
Indeed, any person who does not practice self-denial throughout that day shall be cut off from his kin; and whoever does any work throughout that day, I will cause that person to perish from among his people. Do no work whatever; it is a law for all time, throughout the ages in all your settlements. It shall be a sabbath of complete rest for you, and you shall practice self-denial; on the ninth day of the month at evening, from evening to evening, you shall observe this your sabbath.