If I Could Have a Dollar For Every Time a Scholar Misses the Mark ...

The antitheses in the Sermon on the Mount are also sayings in the first person. Only in the case of the first two does the antithetical form go back to Jesus; the rest have been shaped on that model. In them Jesus sets his 'But I say to you' over against Moses, not to contradict Moses' prohibition of killing and adultery but to develop the motif in order to expose the forbidden actions that happen within people, in their anger and their desires (Matt 5:21, 22; 5:27, 28). He does not say 'You shall not be angry,' or 'You shall not have sexual desires.' He simply says that those who are angry are guilty, and those who lust after someone else's wife have committed adultery. [Gerd Theissen, New Testament p. 19]