Unless your righteousness exceeds: The disciples of Jesus need a new kind of righteousness that only he teaches and makes possible. Matthew 5:21–47 shows this and 5:48 summarizes what it is.
This righteousness is different in amount and quality. Jesus is greater than the temple (12:6) and Jonah (12:41). So, the righteousness of his disciples must greatly surpass that of the Jewish religious teachers and Pharisees (see 3:7–9).