Leviticus 23:24, 39

“Say to the Israelites: ‘On the first day of the seventh month you are to have a day of sabbath rest, a sacred assembly commemorated with trumpet blasts.

“ ‘So beginning with the fifteenth day of the seventh month, after you have gathered the crops of the land, celebrate the festival to the LORD for seven days; the first day is a day of sabbath rest, and the eighth day also is a day of sabbath rest.