Exodus 13:15

American Standard Version

¹⁵ and it came to pass, when Pharaoh ^[a]would hardly let us go, that Jehovah slew all the first-born in the land of Egypt, both the first-born of man, and the first-born of beast: therefore I sacrifice to Jehovah all that openeth the womb, being males; but all the first-born of my sons I redeem.