Exodus 11:9
And the LORD said to Moses, Pharaoh will not hearken to you; that my wonders may be multiplied in the land of Egypt.
Exodus 7:3-4
And I will harden Pharaoh's heart, and multiply my signs and my wonders in the land of Egypt.
Exodus 3:19
And I am sure that the king of Egypt will not let you go, no, not by a mighty hand.
Exodus 10:1
And the LORD said to Moses, Go in to Pharaoh: for I have hardened his heart, and the heart of his servants; that I might show these my signs before him:
Romans 9:16-18
So then, it is not of him that willeth, nor of him that runneth, but of God that showeth mercy.