Charles Ellicott Commentary Zechariah 14:18

"And if the family of Egypt go not up, and come not, neither [shall it be] upon them; there shall be the plague wherewith Jehovah will smite the nations that go not up to keep the feast of tabernacles." — Zechariah 14:18 (ASV)

That have no rain. —This is an impossible rendering of the original. We must read these words in connection with those that follow, and either take the clause as interrogative, and render it, “Then will not (Latin: nonne?) the plague fall upon them with which, etc.,” or we must, with the Septuagint and six Hebrew manuscripts, omit the negative, and render it, then the plague shall fall on them with which, etc.

Lange (quoted by Wright) has correctly observed that if the family of Egypt were to be punished by a deficiency of water, the Abyssinians, even if they attended the feast at Jerusalem, would also have to suffer at the same time.

This is because Egypt can only suffer from water scarcity in conjunction with all the lands south of that country.

Therefore, the fact that withholding rain is described as the specific punishment for the nations that will not go up to the feast is sufficient proof that the prophecy is not to be taken literally.