Exodus 10:23

But all the children of Israel had light in their dwellings— In the midst of every punishment, Jehovah distinguished the Israelites: thus giving ample and constant conviction to the Egyptians, that he was the Sovereign and sole Author of these wonders; and emphatically instructing them, had they been wise enough to have received it, that nothing can harm them, whose confidence is Jehovah: a God, no less tender in mercies to those who obey, than fearful in judgments to those who despise his word.