Exodus 7:3

7:3 But I will harden Pharaoh’s heart, and although I will multiply my signs and my wonders in the land of Egypt,

Exodus 7:13-14

7:13 Yet Pharaoh’s heart became hard, and he did not listen to them, just as the Lord had predicted.

The First Blow: Water to Blood

7:14 The Lord said to Moses, “Pharaoh’s heart is hard; he refuses to release the people.