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.
Berean Study Bible (BSB) - Exodus 13:15 >And when Pharaoh stubbornly refused to let us go, the LORD killed every firstborn in the land of Egypt, both of man and beast. This is why I sacrifice to the LORD the firstborn male of every womb, but I redeem all the firstborn of my sons.’