It seems that this big picture depicts a touching farewell to him lying on his deathbed. But the biblical episode is much more complicated. Elderly half-blind, Jacob blesses the children of his lucky son Joseph, who, having risen, became the chief adviser of the Egyptian pharaoh.
But contrary to custom, he put his right hand, not his left hand, on the head of the younger grandson of Ephraim, and in response to Joseph’s grumble, announced that Ephraim would be higher than the first-born, as numerous people would come from his seed. It has long been expounded as follows: Ephraim will become the progenitor of all Christian nations.
Rembrandt, apparently, follows this tradition, depicting him fair-haired, with a halo around his head. Characteristically, the artist avoids conflicting narration.