"For all the firstborn are mine. When I struck down all the firstborn in Egypt, I set apart for myself every firstborn in Israel, whether human or animal. They are to be mine. I am the LORD."
NIV
For all the firstborn are Mine. On the day that I slew all the firstborn in the land of Egypt, I consecrated for Myself all the firstborn in Israel, both man and beast; Mine they shall be. I am the Lord.
AMP
Because all the firstborn are mine; for on the day that I smote all the firstborn in the land of Egypt I hallowed unto me all the firstborn in Israel, both man and beast: mine shall they be: I am the LORD.
KJV