Exodus 10:1-2

And Jehovah said to Moses, Go in unto Pharaoh; for I have hardened his heart, and the heart of his bondmen, that I might do these my signs in their midst, and that thou mightest tell in the ears of thy son and thy son's son what I have wrought in Egypt, and my signs which I have done among them; and ye shall know that I am Jehovah.