Exodus 9:34

And when Pharaoh saw that the rain and the hail and the thunders were ceased, he sinned yet more, and hardened his heart, he and his servants.

Cross References

Exodus 7:14 And the LORD said unto Moses, Pharaoh's heart is hardened, he refuseth to let the people go.
Exodus 4:21 And the LORD said unto Moses, When thou goest to return into Egypt, see that thou do all those wonders before Pharaoh, which I have put in thine hand: but I will harden his heart, that he shall not let the people go.
Exodus 8:15 But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had said.
2 Chronicles 28:22 And in the time of his distress did he trespass yet more against the LORD: this is that king Ahaz.
2 Chronicles 33:23 And humbled not himself before the LORD, as Manasseh his father had humbled himself; but Amon trespassed more and more.
2 Chronicles 36:13 And he also rebelled against king Nebuchadnezzar, who had made him swear by God: but he stiffened his neck, and hardened his heart from turning unto the LORD God of Israel.
Ecclesiastes 8:11 Because sentence against an evil work is not executed speedily, therefore the heart of the sons of men is fully set in them to do evil.
Romans 2:4-5 Or despisest thou the riches of his goodness and forbearance and longsuffering; not knowing that the goodness of God leadeth thee to repentance? But after thy hardness and impenitent heart treasurest up unto thyself wrath against the day of wrath and revelation of the righteous judgment of God;