Leviticus 23:30-32

23:30 As for any person who does any work on this particular day, I will exterminate that person from the midst of his people! 23:31 You must not do any work. This is a perpetual statute throughout your generations in all the places where you live. 23:32 It is a Sabbath of complete rest for you, and you must humble yourselves on the ninth day of the month in the evening, from evening until evening you must observe your Sabbath.”