I also will choose harsh treatment for them and bring their fears upon them, because when I called, no one answered, when I spoke, they did not listen; but they did what was evil in my eyes and chose that in which I did not delight.
Isaiah 66:4 ESV

God will magnify the sins of the rebellious, like Pharaoh. He does this in part by giving his Law, but “when I spoke, they did not listen.” The Law then becomes a witness against our sins. It exposes them and condemns us accordingly.