What does Genesis 48:13 mean?
Joseph's two oldest sons, Ephraim and Manasseh, are in the process of receiving a blessing—the family blessing—from Joseph's father Jacob. In fact, Jacob has officially pronounced that Joseph's sons now belong to him. He has, in essence, adopted them and put them in the position of his two oldest sons ahead of Reuben and Simeon (Genesis 48:1–12).In the previous verses, Joseph repositioned his sons so he could bow in an expression of great respect and appreciation for his father. Now Joseph moves his two sons into position again. Joseph positions them according to birth order. Lined up three across before Jacob's lap, Joseph places Ephraim on his own right side so that Jacob's left hand will be on Ephraim's head for the blessing. He places Manasseh on his left so that Jacob's right hand will be on his head. Since Manasseh is the oldest, every custom and legal proceeding of the time would demand that he be the one to receive the greater blessing, indicated by the right hand of the one giving the blessing.
Joseph's action was an honorable one. He was helping his blind father to get the blessing right. Jacob, however, will counter Joseph's efforts (Genesis 48:14).