Charles Ellicott Commentary Deuteronomy 9:1

"Hear, O Israel: thou art to pass over the Jordan this day, to go in to dispossess nations greater and mightier than thyself, cities great and fortified up to heaven," — Deuteronomy 9:1 (ASV)

Hear, O Israel. —A fresh portion of the exhortation begins here. The cause of Israel’s conquest of Canaan is not to be sought in their own merit, but in the choice of Jehovah.

You are to pass. —Literally, you are passing: i.e., just about to pass.

Nations greater and mightier than yourself. —If this is true (and there is no reason to doubt it), the responsibility of the conquest does not rest with Israel; they were the Divine executioners. (See Note on Joshua 5:13-14.)

Cities ... fenced up to heaven. —Compare the expression in Genesis 11:4, a city and a tower whose top may reach to (literally, is in) heaven. So here, cities great and fortified in the heavens. Was St. Paul thinking of this expression when he said, We wrestle against spiritual wickedness in the heavenly regions? (Ephesians 6:12).