‘And it came to be, when Pharaoh was too hardened to let us go, that יהוה killed every first-born in the land of Mitsrayim, both the first-born of man and the first-born of beast. Therefore I am slaughtering to יהוה every male that open the womb, but every first-born of my sons I ransom.’
And יהוה said to Mosheh, “As you go back to Mitsrayim, see that you do all those wonders before Pharaoh which I have put in your hand. But I am going to harden his heart, so that he does not let the people go.
And יהוה said to Mosheh, “Now see what I do to Pharaoh, for with a strong hand he is going to let them go, and with a strong hand he is going to drive them out of his land.”