kjv@Numbers:3:41 @ And thou shalt take the Levites for me (I am the LORD)...instead of all the firstborn among...
kjv@1Chronicles:5:1 @...sons of Reuben the firstborn of...(for he was the firstborn; but, forasmuch as he defiled his father's bed, his birthright was given unto the sons of Joseph the son of Israel: and the genealogy is not to be reckoned after the birthright.