Leviticus 23:41-44

23:41 You must celebrate it as a pilgrim festival to the Lord for seven days in the year. This is a perpetual statute throughout your generations; you must celebrate it in the seventh month. 23:42 You must live in temporary shelters for seven days; every native citizen in Israel must live in temporary shelters, 23:43 so that your future generations may know that I made the Israelites live in temporary shelters when I brought them out from the land of Egypt. I am the Lord your God.’”

23:44 So Moses spoke to the Israelites about the appointed times of the Lord.