Matthew 5:28-29

but I say to you that everyone who [so much as] looks at a woman with lust for her has already committed adultery with her in his heart. If your right eye makes you stumble and leads you to sin, tear it out and throw it away [that is, remove yourself from the source of temptation]; for it is better for you to lose one of the parts of your body, than for your whole body to be thrown into hell.