But Israel, crossing his hands, put out his right hand and laid it on the head of Ephraim, although he was the younger, and his left hand on the head of Manasseh, although he was the firstborn.
Indeed, all the firstborn among the Israelites, human being and beast alike, belong to me; I consecrated them to myself on the day I killed all the firstborn in the land of Egypt.
and from among the Israelites I have given to Aaron and his sons these Levites, who are to be dedicated, to perform the service of the Israelites in the tent of meeting and to make atonement for them, so that no plague may strike among the Israelites should they come too near the sanctuary.