The Feast of Tabernacles, which is the last feast of all the feasts ordained by God for His people (Lev. 23:34, 39-43), is for Israel's enjoyment of the rich produce of the good land at its harvest time for their satisfaction.
Christ is our good land with all its produce for our enjoyment and satisfaction.
He cried out on the last day of the feast, saying, "If anyone thirsts, let him come to Me and drink. He who believes into Me, as the Scripture said, out of his innermost being shall flow rivers of living water" (John 7:37-38). The Feast of Tabernacles was just a type of Christ as the reality. That feast did not satisfy them, so on the last day the Lord cried out that whoever is thirsty, unsatisfied, should come to Him to drink for their real satisfaction.
This call is repeated by the Spirit with the bride for people to participate in the enjoyment of Christ in the New Jerusalem in John's last book, that is, the book of Revelation (22:17).
This indicates that the people who held the Feast of Tabernacles were not satisfied; the real satisfaction was to receive Christ and drink of Him that they would be not only satisfied but also overflowing with rivers of living water. This overflow of the riches is the expressed riches, the fullness. Originally all the riches were contained in God, but now they become our enjoyment to such an extent that they overflow to express the riches of our enjoyment of God.