The feast of tabernacles was a feast held to commemorate the Israelites time of sojourning in the wilderness (40 years). Israel lived in tents (booths) the entire time.

Leviticus 23:42 Ye shall dwell in booths seven days; all that are Israelites born shall dwell in booths:

43 That your generations may know that I made the children of Israel to dwell in booths, when I brought them out of the land of Egypt: I am the LORD your God.

Jonah, at God's direction, proclaimed the following to Nineveh:

Jonah 3:4 And Jonah began to enter into the city a day's journey, and he cried, and said, Yet forty days, and Nineveh shall be overthrown.

What did Jonah do after proclaiming that God would destroy Nineveh in 40 days?

The Bible tells us that he went outside the city and built himself a booth (tabernacle):

Jonah 4:5 So Jonah went out of the city, and sat on the east side of the city, and there made him a booth, and sat under it in the shadow, till he might see what would become of the city.

How long did Jonah sit under the booth (tabernacle) he had made?

Obviously, he sat under the booth until the 40 day period expired.

This is very strong evidence pointing to the feast of tabernacles being observed for a period of 40 years. Israel observed it for 40 years in the wilderness; and Jonah observed it until the completion of a 40 day period regarding Nineveh.

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