Charles Ellicott Commentary Deuteronomy 33:13

"And of Joseph he said, Blessed of Jehovah be his land, For the precious things of heaven, for the dew, And for the deep that coucheth beneath," — Deuteronomy 33:13 (ASV)

And of Joseph he said. —The remark of Rashi is especially applicable here. “You will find in the case of all the tribes, that the blessing of Moses is drawn from the fountain of the blessing of Jacob.”

As the voice of Judah, the office of Levi, and the situation of Benjamin are singled out for notice, so the land of Joseph is blessed.

The deep that coucheth beneath. —Rashi observes that “the deep ascends in vapour, and also gives moisture from below.”