Jesus affirms in Matthew 5 that he did not come to abolish the Law. We see an example of this in the famous account of his response to the woman caught in adultery - John 8. Though her sin was real, the law actually protected her from her accusers--whose true aim was not to promote righteousness but to trap Jesus. The mercy of God is not revealed by setting aside the law, but by fulfilling it, and the ultimate fulfillment is Jesus himself bearing the penalty for our sin.