“Do not think that I have come to abolish the law or the prophets. I have come not to abolish but to fulfill. Amen, I say to you, until heaven and earth pass away, not the smallest letter or the smallest part of a letter will pass from the law, until all things have taken place…I tell you, unless your righteousness surpasses that of the scribes and Pharisees, you will not enter into the kingdom of heaven.
“You have heard that it was said to your ancestors, ‘You shall not kill; and whoever kills will be liable to judgment.’ But I say to you, whoever is angry with his brother will be liable to judgment,…
“You have heard that it was said, ‘You shall not commit adultery.’ But I say to you, everyone who looks at a woman with lust has already committed adultery with her in his heart. …
“It was also said, ‘Whoever divorces his wife must give her a bill of divorce.’ But I say to you, whoever divorces his wife (unless the marriage is unlawful)…
“Again you have heard that it was said to your ancestors, ‘Do not take a false oath, but make good to the Lord all that you vow.’…
Let your ‘Yes’ mean ‘Yes,’ and your ‘No’ mean ‘No.’ Anything more is from the evil one. (Mt 5:17-37)
Jesus says that he has come to fulfil the law and the prophets. But the Pharisees consider him to be a man who breaks the law. He broke the Sabbath laws; he and his disciples broke the law of purification and fasting etc. How could Jesus say that he has come to fulfil the law. He also warns the followers to be vigilant about the practices of the Pharisees and the scribes. So who fulfilled the law Jesus or the Pharisees?
Jesus clearly explains this by saying it is not the external practices that matters (though at the end it will come to that) rather it is the attitude of the person towards the law and the practice of it. He gives examples for this. It is not the killing or committing adultery or divorce or taking an oath that is bad (though they will in the end). But the anger that slowly turns one to be a murderer and the lustful look that leads one to sin etc are to be considered seriously.
Let your ‘Yes’ mean ‘Yes,’ and your ‘No’ mean ‘No.’ Anything more is from the evil one. This is a strong statement from the mouth of Jesus. By saying this Jesus tells his listeners to mean what they say. Any statements of compromise or hazy statements should not be found among his followers. His followers are asked to be clear about not letting the evil one to play between what they say and what they mean.