And Jehovah said unto Moses, When thou goest back into Egypt, see that thou do before Pharaoh all the wonders which I have put in thy hand: but I will harden his heart and he will not let the people go.
And Jehovah said unto Moses, Stretch out thy hand toward heaven, that there may be darkness over the land of Egypt, even darkness which may be felt.
But Jehovah hardened Pharaoh's heart, and he would not let them go.