Exodus 14:16-17

16You yourself must do this: Lift up your stick and hold your hand out over the sea. The water will become two separate parts. Then the Israelites can cross through the middle of the sea on dry ground.

17This is what I, the Lord, will do: I will cause the minds of the Egyptians to become hard. They will follow the Israelites into the sea to catch them. I will show how great I am when I win against Pharaoh and all his army, his chariots, his horses and their riders.