Bible Verses About Feast of Tabernacles: Penalty for not observing

Finally, everyone remaining from all the nations that came to attack Yerushalayim will go up every year to worship the king, ADONAI-Tzva'ot, and to keep the festival of Sukkot.

If any of the families of the earth does not go up to Yerushalayim to worship the king, ADONAI-Tzva'ot, no rain will fall on them.

If the family of Egypt doesn't go up, if they refuse to come, they will have no [annual] overflow [from the Nile]; moreover, there will be the plague with which ADONAI will strike the nations that don't go up to keep the festival of Sukkot.

This will be Egypt's punishment and the punishment of all the nations that don't go up to keep the festival of Sukkot.