Exodus 13:15

In Exodus 13 of Exodus.

And it came to pass, when Pharaoh would hardly let us go, that the LORD slew all the firstborn in the land of Egypt, both the firstborn of man, and the firstborn of beast: therefore I sacrifice to the LORD all that openeth the matrix, being males; but all the firstborn of my children I redeem.

The King James Version (1769) is in the public domain in the United States.