37 "These are the appointed feasts of God which you will decree as sacred assemblies for presenting Fire-Gifts to God: the Whole-Burnt-Offerings, Grain-Offerings, sacrifices, and Drink-Offerings assigned to each day. 38 These are in addition to offerings for God's Sabbaths and also in addition to other gifts connected with whatever you have vowed and all the Freewill-Offerings you give to God 39 "So, summing up: On the fifteenth day of the seventh month, after you have brought your crops in from your fields, celebrate the Feast of God for seven days. The first day is a complete rest and the eighth day is a complete rest.

Matthew Henry's Commentary on Leviticus 23:37-39

Commentary on Leviticus 23:33-44

(Read Leviticus 23:33-44)

In the feast of Tabernacles there was a remembrance of their dwelling in tents, or booths, in the wilderness, as well as their fathers dwelling in tents in Canaan; to remind them of their origin and their deliverance. Christ's tabernacling on earth in human nature, might also be prefigured. And it represents the believer's life on earth: a stranger and pilgrim here below, his home and heart are above with his Saviour. They would the more value the comforts and conveniences of their own houses, when they had been seven days dwelling in the booths. It is good for those who have ease and plenty, sometimes to learn what it is to endure hardness. The joy of harvest ought to be improved for the furtherance of our joy in God. The earth is the Lord's, and the fullness thereof; therefore whatever we have the comfort of, he must have the glory of, especially when any mercy is perfected. God appointed these feasts, "Beside the sabbaths and your free-will offerings." Calls to extraordinary services will not excuse from constant and stated ones.