Leviticus 23:39-43

39 Now, the fifteenth day of the seventh month, when you have gathered in the produce of the land, you shall keep the festival of the Lord, lasting seven days; a complete rest on the first day, and a complete rest on the eighth day.
40 On the first day you shall take the fruit of majestic trees, branches of palm trees, boughs of leafy trees, and willows of the brook; and you shall rejoice before the Lord your God for seven days.
41 You shall keep it as a festival to the Lord seven days in the year; you shall keep it in the seventh month as a statute forever throughout your generations.
42 You shall live in booths for seven days; all that are citizens in Israel shall live in booths,
43 so that your generations may know that I made the people of Israel live in booths when I brought them out of the land of Egypt: I am the Lord your God.