He blessed Joseph, not now in his person, but in his children, which yet is called here a blessing of Joseph, because they were a part of himself. In which sense, and upon the same ground, the land of Canaan is ofttimes said to be not only promised, but given to Abraham and Isaac, & c., not as if they were in person to possess it, but because it should be given to their children. Thus Ham is said to be cursed when his son is cursed, Genesis 9:25. Which fed me, i.e. protected, sustained, and directed me.
Related Commentaries of Genesis 48:15
Genesis 48:15
15 And he blessed Joseph, and said, God, before whom my fathers Abraham and Isaac did walk, the God which fed me all my life long unto this day,