Leviticus 23:37-40

37‘These are 1the appointed times of the Lord which you shall proclaim as holy convocations, to present offerings by fire to the Lord--burnt offerings and grain offerings, sacrifices and drink offerings, 2each day’s matter on its own day-- 38besides those of the sabbaths of the Lord, and besides your gifts and besides all your 3votive and freewill offerings, which you give to the Lord.

39‘On exactly the fifteenth day of the seventh month, 4when you have gathered in the crops of the land, you shall celebrate the feast of the Lord for seven days, with a 5rest on the first day and a 6rest on the eighth day. 40Now on the first day you shall take for yourselves the 7foliage 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.