His glory is like the firstling of his bullock - This similitude is very obscure. A bullock was the most excellent of animals among the Jews, not only because of its acceptableness in sacrifice to God, but because of its great usefulness in agriculture. There is something peculiarly noble and dignified in the appearance of the ox, and his greatest ornament are his fine horns; these the inspired penman has particularly in view, as the following clause proves; and it is well known that in Scriptural language horns are the emblem of strength, glory, and sovereignty; Psalm 75:5, Psalm 75:10; Psalm 89:17, Psalm 89:24; Psalm 112:9; Daniel 8:3, etc.; Luke 1:69; Revelation 17:3, etc.
His horns are like the horns of unicorns - ראם reem, which we translate unicorn, from the μονοκερως monokeros of the Septuagint, signifies, according to Bochart, the mountain goat; and according to others, the rhinoceros, a very large quadruped with one great horn on his nose, from which circumstance his name is derived. See the notes on Numbers 23:22; Numbers 24:8. Reem is in the singular number, and because the horns of a unicorn, a one-horned animal, would have appeared absurd, our translators, with an unfaithfulness not common to them, put the word in the plural number.
To the ends of the earth - Of the land of Canaan, for Joshua with his armies conquered all this land, and drove the ancient inhabitants out before him.
They are the ten thousands of Ephraim, etc. - That is, The horns signify the ten thousands of Ephraim, and the thousands of Manasseh. Jacob prophesied, Genesis 48:19, that the younger should be greater than the elder; so here Tens of thousands are given to Ephraim, and only thousands to Manasseh. See the census, Numbers 1:33-35; (note).
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, i. e., Ephraim and Manasseh, would undergo (compare Genesis 49:23-24); while the lawgiver seems to look beyond, and to behold the two triumphant and established in their power.
Rather: “The first-born of his” (i. e. Joseph‘s) “bullock is his glory”: the reference being 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, i. e., of Joseph‘s offspring. The ox is a common emblem of power and strength.