John Calvin Commentary Deuteronomy 33:15

"And for the chief things of the ancient mountains, And for the precious things of the everlasting hills," — Deuteronomy 33:15 (ASV)

And for the chief things of the ancient mountains. In these words, he shows that no part of the land would be barren.

We know that the tops of mountains are generally uncultivated or, at any rate, bear nothing but trees that have no fruit. But Moses affirms that even there also, the richest produce will be found.

For this reason, at least in my opinion, he calls the mountains ancient, and the hills lasting, as if they were very highly renowned. Their antiquity is not praised as if they were created before the rest of the world; rather, these mountains are honorably distinguished as the first-born because God’s blessing eminently rests upon them.

Thus, in the blessing of Jacob it is said, unto the utmost bound of the everlasting hills, as if to say that no corner of these most celebrated mountains would be devoid of fertility (Genesis 49:26).

In the next verse, he generally extends to the whole land what he had said of the mountains.

Those who translate what follows as: On account of the good-will of the dweller in the bush the blessing shall come;—greatly misunderstand Moses’ meaning. And his rendering is altogether barbarous who translates it as: On account of the piety, etc.

My opinion is that the word רצון (retzon), is in the nominative case; for it is quite in accordance with the context that the favor of God would come upon the head of Joseph; for after Moses had magnified God's bounty, he now points out its source or cause, namely, that this extraordinary fertility was the result of God’s gratuitous favor.

The words of Jacob, by the God of thy father, and by the Almighty, exactly correspond with this. There I have also explained why Joseph was called a Nazarene among his brothers.³²¹

God is called the dweller in the bush by periphrasis, with reference to the vision that was presented to Moses on Mount Sinai; for God then appeared a second time as the Redeemer and Father of His people, after having made His covenant with Abraham and Jacob. And this serves as confirmation, as if to say that the same God who had formerly blessed Joseph by the mouth of His servant Jacob now repeated the same prophecy to give fuller assurance of its truth.

³²¹ A. V., “Separated from his ., “Separated from his brethren.” See on ” See on Genesis 49:26, , C. Soc. Edit., vol. 2, p. 470..