Exodus 10:1-2

Then the LORD said to Moses, “Go to Pharaoh, for I have hardened his heart and the heart of his servants [making them determined and unresponsive], so that I may exhibit My signs [of divine power] among them, and that you may recount and explain in the hearing of your son, and your grandson, what I have done [repeatedly] to make a mockery of the Egyptians—My signs [of divine power] which I have done among them—so that you may know [without any doubt] and recognize [clearly] that I am the LORD.”