Genesis 48:17

When Joseph observed his father placing his right hand upon the head of Ephraim, the younger son, he laid hold of it to put it upon Manasseh's head, telling his father at the same time that he was the first-born; but Jacob replied, "I know, my son, I know: he also (Manasseh) will become a nation, and will become great, yet (ואוּלם as in Gen 28:19) his younger brother will become greater than he, and his seed will become the fulness of nations." This blessing began to be fulfilled from the time of the Judges, when the tribe of Ephraim so increased in extent and power, that it took the lead of the northern tribes and became the head of the ten tribes, and its name acquired equal importance with the name Israel, whereas under Moses, Manasseh had numbered 20,000 more than Ephraim (Num 26:34 and Num 26:37). As a result of the promises received from God, the blessing was not merely a pious wish, but the actual bestowal of a blessing of prophetic significance and force. - In Gen 48:20 the writer sums up the entire act of blessing in the words of the patriarch: "In thee (i.e., Joseph) will Israel (as a nation) bless, saying: God make thee as Ephraim and Manasseh" (i.e., Joseph shall be so blessed in his two sons, that their blessing will become a standing form of benediction in Israel); "and thus he placed Ephraim before Manasseh," viz., in the position of his hands and the terms of the blessing. Lastly, (Gen 48:21) Israel expressed to Joseph his firm faith in the promise, that God would bring back his descendants after his death into the land of their fathers (Canaan), and assigned to him a double portion in the promised land, the conquest of which passed before his prophetic glance as already accomplished, in order to insure for the future the inheritance of the adopted sons…

The time drawing nigh that Israel must die, having, in the former chapter, given order about his burial, in this he takes leave of his grand-children by Joseph, and in the next of all his children. Thus Jacob's dying words are recorded, because he then spoke by a spirit of prophecy; Abraham's and Isaac's are not. God's gifts and graces shine forth much more in some saints than in others upon their death-beds. The Spirit, like the wind, blows where it listeth. In this chapter, I. Joseph, hearing of his father's sickness, goes to visit him, and takes his two sons with him (Gen 48:1, Gen 48:2). II. Jacob solemnly adopts his two sons, and takes them for his own (Gen 48:3-7). III. He blesses them (Gen 48:8-16). IV. He explains and justifies the crossing of his hands in blessing them (Gen 48:17-20). V. He leaves a particular legacy to Joseph (Gen 48:21, Gen 48:22).

48:17-19 Joseph was upset: He expected God to act according to convention, but faith recognizes that God’s ways are not man’s ways, and God’s thoughts are not man’s thoughts. It took Jacob a lifetime to learn this lesson, but he did learn it, and here he acted on it.