15 And when Pharaoh made his heart hard and would not let us go, the Lord sent death on all the first sons in Egypt, of man and of beast: and so every first male who comes to birth is offered to the Lord; but for all the first of my sons I give a price.
Exodus 13:15 Cross References - BBE
Exodus 12:29
29 And in the middle of the night the Lord sent death on every first male child in the land of Egypt, from the child of Pharaoh on his seat of power to the child of the prisoner in the prison; and the first births of all the cattle.