Leviticus 23:40-43

Now on the first day you shall take for yourselves the foliage of beautiful trees, palm branches and boughs of leafy trees and willows of the brook, and you shall rejoice before the LORD your God for seven days. You shall thus celebrate it as a feast to the LORD for seven days in the year. It shall be a perpetual statute throughout your generations; you shall celebrate it in the seventh month. You shall live in booths for seven days; all the native-born in Israel shall live in booths, so that your generations may know that I had the sons of Israel live in booths when I brought them out from the land of Egypt. I am the LORD your God.’ ”