Leviticus 23:23-25

ADONAI spoke to Moses saying: “Speak to Bnei-Yisrael, saying: In the seventh month, on the first day of the month, you are to have a Shabbat rest, a memorial of blowing (shofarot), a holy convocation. You are to do no regular work, and you are to present an offering made by fire to ADONAI.”