And now thy two sons, Ephraim and Manasseh
Ephraim was the youngest, but is mentioned first, as he afterwards was preferred in the blessing of him: which were born unto thee in the land of Egypt, before I came unto
thee into Egypt;
and therefore must be twenty years of age, or upwards: for Jacob had been in Egypt seventeen years, and he came there when there had been two years of famine, and Joseph's sons were born to him before the years of famine began, ( Genesis 41:50 ) ; of these Jacob says, they [are] mine: as Reuben and Simeon, they shall be mine;
that is, by adoption; should be reckoned not as his grandchildren, but as his children, even as his two eldest sons, Reuben and Simeon; and so should be distinct tribes or heads of them, as his sons would be, and have a distinct part and portion in the land of Canaan; and thus the birthright was transferred from Reuben, because of his incest, to Joseph, who in his posterity had a double portion assigned him.