Exodus 11:10
And Moses and Aaron did all these wonders before Pharaoh: and the LORD hardened Pharaoh’s heart, so that he would not let the children of Israel go out of his land. And Moses and Aaron did all these wonders before Pharaoh: and the LORD hardened Pharaoh’s heart, so that he would not let the children of Israel go out of his land.
Exodus 11:10 stands as the closing summary of the whole series of wonders performed by Moses and Aaron in Pharaoh's presence. Those wonders were a revelation of Jehovah's supremacy over all rival powers. At the same time they laid bare the utter powerlessness of the idols Egypt trusted and worshiped. They carried a direct demand that Israel be set free from bondage in Egypt. The final plague crowning the series was an act of judgment making manifest that Jehovah executes judgment upon the earth.