Matthew 6:23
But if your eyes are bad, your whole body will be full of darkness. If then the light within you is darkness, how great is that darkness!
What it says
Bad sight fills the body with darkness and exposes darkness that calls itself light.
What it is doing
It warns that inward darkness can occupy the place of light.
In context
22The eye is the lamp of the body. If your eyes are good, your whole body will be full of light. 23But if your eyes are bad, your whole body will be full of darkness. If then the light within you is darkness, how great is that darkness! 24No one can serve two masters: Either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve both God and money.