Matthew 5:27,28

Ye have heard, &c.— What has been hitherto said refers to meekness; what now follows, to purity of heart. Dr. Lightfoot, to explain the opinion of the Jewish doctors, respecting the duty of this seventh commandment, cites the Targum upon Exodus 20 by which it appears, that they were very loose moralists indeed. In opposition therefore to them, our Lord declared, that whosoever looketh on a woman, &c. whosoever cherishes unchaste desires and intentions, or, as it is expressed in the tenth commandment, covets his neighbour's wife, is really guilty of adultery, though he should never find the opportunity of committing the act with her; for which cause, all such use of our senses, as inflames the mind with lust, must be carefully avoided. See on the next verse, and Eccliasticus 9:5, &c.