Matthew 6:22
The eyes are like a lamp for the body. If your eye is clear (simple) (focused) (single minded), your whole body will be full of [spiritual] light.
Luke 11:34-36
The lamp of your body is your eye. When your eye is clear your entire body is full of light. When it is evil your body is full of darkness.
2 Corinthians 11:3
But I fear, lest by any means, as the serpent beguiled Eve in his craftiness, your minds will be lead away from the simplicity and the purity (cleanness) that is toward Christ.
Colossians 3:22
Servants, obey your masters according to the flesh in all things, not with eye-service, as men-pleasers, but in singleness of heart, respecting God.
Acts 2:46
They continued daily with one accord in the temple, and breaking bread from house to house. They ate their food with gladness and singleness of heart.
Ephesians 6:5
Servants, be obedient to those who according to the flesh are your masters, with fear and trembling, in sincerity of your heart, as to Christ.