Leviticus 23:24, 39

“Say to the children of Israel, ‘On the first day of the seventh month (almost October), you shall observe a day of solemn sabbatical rest, a memorial day announced by the blowing of trumpets, a holy convocation.

‘On exactly the fifteenth day of the seventh month (nearly October), when you have gathered in the crops of the land, you shall celebrate the feast of the LORD for seven days, with a Sabbath rest on the first day and a Sabbath rest on the eighth day.