Exodus 14:4-5

4I will harden (make stubborn, defiant) Pharaoh’s heart, so that he will pursue them; and I will be glorified and honored through Pharaoh and all his army, and the Egyptians shall know [without any doubt] and acknowledge that I am the Lord.” And they did so.

5When the king of Egypt was told that the people had fled, Pharaoh and his servants had a change of heart toward the people, and they said, “What is this that we have done? We have let Israel go from serving us!”