Genesis 48:14

48:14 Israel stretched out his right hand and placed it on Ephraim’s head, although he was the younger. Crossing his hands, he put his left hand on Manasseh’s head, for Manasseh was the firstborn.

Genesis 48:20

48:20 So he blessed them that day, saying,

“By you will Israel bless, saying,

‘May God make you like Ephraim and Manasseh.’”

So he put Ephraim before Manasseh.