That thou shall set apart to the LORD all that openeth the matrix; and every firstling that cometh of a beast which thou hast, the males shall be the LORD'S.

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