Matthew 5:28
"But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart."
Cross References (ranked by relevance)
Lust not after her beauty in thine heart; neither let her take thee with her eyelids.
Thou shalt not covet thy neighbour’s house, thou shalt not covet thy neighbour’s wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbour’s.
And it came to pass in an eveningtide, that David arose from off his bed, and walked upon the roof of the king’s house: and from the roof he saw a woman washing herself; and the woman was very beautiful to look upon.
I made a covenant with mine eyes; why then should I think upon a maid?
And when Shechem the son of Hamor the Hivite, prince of the country, saw her, he took her, and lay with her, and defiled her.
Having eyes full of adultery, and that cannot cease from sin; beguiling unstable souls: an heart they have exercised with covetous practices; cursed children:
If mine heart have been deceived by a woman, or if I have laid wait at my neighbour’s door;
For we know that the law is spiritual: but I am carnal, sold under sin.
I have seen an end of all perfection: but thy commandment is exceeding broad.
But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.
But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire.