John Gill Commentary Ezekiel 12:20

"And the cities that are inhabited shall be laid waste, and the land shall be a desolation; and ye shall know that I am Jehovah." — Ezekiel 12:20 (ASV)

And the cities that are inhabited shall be laid waste Not only the city of Jerusalem, but the other cities of Judea; as they were by the Chaldeans, which were then full of inhabitants.

and the land shall be desolate; The whole land of Judea be destitute of men and cattle, and lie uncultivated, and become barren and unfruitful.

and you shall know that I [am] the Lord; who were then captives in Babylon, as well as those who should be dispersed among the nations would; see (Ezekiel 12:15Ezekiel 12:16) .