Albert Barnes Commentary Deuteronomy 33:13-17

"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, And for the precious things of the fruits of the sun, And for the precious things of the growth of the moons, And for the chief things of the ancient mountains, And for the precious things of the everlasting hills, And for the precious things of the earth and the fulness thereof, And the good will of him that dwelt in the bush. Let [the blessing] come upon the head of Joseph, And upon the crown of the head of him that was separate from his brethren. The firstling of his herd, majesty is his; And his horns are the horns of the wild-ox: With them he shall push the peoples all of them, [even] the ends of the earth: And they are the ten thousands of Ephraim, And they are the thousands of Manasseh." — Deuteronomy 33:13-17 (ASV)

Comparing the words of Moses with those of Jacob, it will be seen that the patriarch dwells with emphasis on the severe conflicts which Joseph, that is, Ephraim and Manasseh, would undergo ; while the lawgiver seems to look beyond, and to behold the two triumphant and established in their power (Deuteronomy 33:17).

Rather: “The first-born of his” (that is, Joseph’s) “bullock is his glory”: the reference is to Ephraim, who was raised by Jacob to the honors of the firstborn (Genesis 48:20), and is here likened to the firstling of Joseph’s oxen, that is, of Joseph’s offspring. The ox is a common emblem of power and strength.