for all the firstborn are Mine. On the day I struck down every firstborn in the land of Egypt, I consecrated to Myself all the firstborn in Israel, both man and beast. They are Mine; I am the LORD.”
KJV
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.
ASV
for all the first-born are mine; on the day that I smote all the first-born in the land of Egypt I hallowed unto me all the first-born in Israel, both man and beast; mine they shall be: I am Jehovah.