Luke 10:28 - Ellicott's Commentary On The Whole Bible

Thou hast answered right. — The acceptance of the lawyer’s answer as theoretically true was part of the method of our Lord’s teaching. The words that followed, “This do, and thou shalt live,” were those of a Prophet who knew what was in the man, and read the secrets of his heart, and saw how little love was to be found there. In the command “This do...,” however, our Lord does something more than accommodate Himself to the legal point of view. Love was really life, at once its source and its manifestation, if only the love were true, and the test of its being true was action.