Leviticus 23:39-40

39‘Also on the fifteenth day of the seventh month, when you have gathered in the fruit of the land, you shall keep the feast of the Lord for seven days; on the first day there shall be a sabbath-rest, and on the eighth day a sabbath-rest.

40And you shall take for yourselves on the first day the fruit of beautiful trees, branches of palm trees, the boughs of leafy trees, and willows of the brook; and you shall rejoice before the Lord your God for seven days.