“That isn’t a toy!” parents warn a child playing with a knife or a hammer.
Pharaoh thought he could play a game with God and win. He lost.
Your heart is not a toy.
The story of God’s battle with Pharaoh in the book of Exodus is the story of the consequences of a hardened heart. It’s the story of someone who thought they could toy with God and with their heart. We cannot.
In the first five plagues, Pharaoh’s hardens his heart three times and his heart “is hardened” (it’s ambiguous who is doing the hardening) twice.