Genesis 48:17-18

17When Joseph saw that his father laid his right hand on Ephraim’s head, it displeased him [because he was not the firstborn]; and he grasped his father’s hand to move it from Ephraim’s head to Manasseh’s head.

18Joseph said to his father, “Not so, my father, for this is the firstborn; place your right hand on Manasseh’s head.”