The righteousness of the disciples of Jesus must exceed that of the Scribes and Pharisees whose standard of religious piety and practice was high. These of course did what they did only to be seen by people and to show off their piety. The disciples are called not merely to avoid being hypocritical.
In the six antitheses (-48) that follow, Matthew shows what it means in practice for the righteousness of the disciples to exceed that of the Scribes and Pharisees. Each of the six begins with what was said of old and what Jesus is now saying. In these verses (-26) Matthew narrates first of the six, which is about the Torah’s prohibition of murder (Exodus ; Deut ). The supplementary “whoever murders shall be liable to judgement” is not found verbatim anywhere in the Old Testament, and seems to have been added by Matthew to introduce the word “judgement” which he uses in the next verse. After stating the law and adding a supplementary, the Matthean Jesus then radicalises the law and calls for an interiorization of it (). The call seems to be to submit one’s thoughts about other people, as well as the words they give rise to, to God’s penetrating judgement. It is a call to realize that God wills not only that human beings not kill each other but also that there be no hostility between human beings. The next verses (-26) are an application of what Jesus says. Reconciliation is even more important than offering worship and sacrifice. The disciples are called to work for reconciliation in the light of the eschatological judgement toward which they are journeying.
If we come to worship God and there are feelings of anger, revenge or hatred in our hearts, then our worship remains incomplete. It is only an external worship and not true worship. God does not need our adoration, but if want to adore him it must also come from within.