Rashi on Deuteronomy 33:17/רש"י על דברים ל״ג:י״ז

1בכור שורו THE FIRSTBORN OF HIS OX — There is a usage of the word בכור that denotes greatness and sovereignty, as it is said, (Psalms 89:28) “I will also make him a בכור” (i.e., a man of rank), and similarly (Exodus 4:22) “My son, my firstborn (בכורי) is Israel”. The text means: the king who will issue from him, and that is Joshua, whose strength will be mighty as that of an ox to subdue many kings,

2הדר לו HONOUR TO HIM — i.e., honour is given unto him, as it is said, (Numbers 27:20) “And thou shalt give of thy honour (הודך, a synonym of הדר) unto him” (Joshua).

3וקרני ראם קרניו AND HIS HORNS ARE THE HORNS OF A RE’EM — The ox — its strength is mighty but its horns are not beautiful, a Re’em, however — its horns are beautiful but its strength is not mighty: therefore it ascribes to Joshua the strength of an ox and the beauty of a Re’em’s horns (Sifrei Devarim 353:10).

4אפסי ארץ [NATIONS] OF THE ENDS OF THE EARTH — The thirty-one kings whom Joshua conquered — is it possible that they were all of the land of Israel? But there was no king or ruler who did not acquire for himself a palace and territory in the land of Israel because it was so estimable to all of them (Sifrei Devarim 353:12), as it is said of Palestine, (Jeremiah 3:19) “An inheritance, the desire of hosts of nations” (see Rashi on this verse).

5והם רבבות אפרים AND THEY ARE THE MYRIADS OF EPHRAIM — i.e., those who are gored are the myriads whom Joshua, who was descended from Ephraim, slew.

6והם אלפי מנשה AND THEY ARE THE THOUSANDS OF MANASSEH — they are the thousands whom Gideon, who was descended from Manasseh, slew of Midian, as it is said, (Judges 8:10) “And Zebah and Zalmunna were in Karkor [and their hosts with them, about fifteen thousand men, all that were left … for there had fallen a hundred and twenty thousand men that drew sword]”.