the eye
Proverbs Chapter 7:2
Keep my commandments, and live; and my law as the apple of thine eye.
Matthew Chapter 6:22
The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light.
Matthew Chapter 6:23
But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!
Luke Chapter 11:34
The light of the body is the eye: therefore when thine eye is single, thy whole body also is full of light; but when thine eye is evil, thy body also is full of darkness.