John Calvin Commentary Genesis 48:5

"And now thy two sons, who were born unto thee in the land of Egypt before I came unto thee into Egypt, are mine; Ephraim and Manasseh, even as Reuben and Simeon, shall be mine." — Genesis 48:5 (ASV)

And now your two sons. Jacob confers on his son the special privilege that he, being one person, should establish two tribal heads; that is, that his two sons should inherit an equal right with their uncles, as if they were primary heirs.

But what is this! That a decrepit old man assigns to his grandchildren, as a royal patrimony, a sixth part of the land in which he had entered as a stranger, and from which he is now an exile once more! Who would not have said that he was dealing in fables? It is a common proverb that no one can give what he does not have.

What, therefore, did Joseph gain by being established, through an imaginary title, as lord of that land—a land in which its donor was barely allowed to drink the very water he had dug for with great effort, and from which, eventually, famine expelled him?

But from this it appears with what firm faith the holy patriarchs relied upon the word of the Lord, since they chose rather to depend on His words than to possess a permanent dwelling in the land.

Jacob is dying as an exile in Egypt; yet, meanwhile, he calls the governor of Egypt away from his high position into exile, so that Joseph might be truly well and happy.

Joseph, because he acknowledges his father as a prophet of God who speaks no fabrications of his own, esteems the dominion offered to him—which has not yet materialized—as highly as if it were already in his possession.

Moreover, Jacob’s command that any other sons of Joseph (if he were to have others) be counted among the families of these two brothers is as if he directed them to be adopted by the two whom he adopts for himself.