Reading these verses it is easy to forget that the Father is speaking to his child. The Father wants his beloved child to be mindful of the heart and the future. When the Father teaches about a scoundrel and a villain he wants his juvenile to look inward more than outward.
A wicked person uses their mouth, eyes, feet, fingers, and any other form of communication in devious ways to achieve the deceitful plots of their heart (13). Such ploys harm others. The Father does not want his children to harm others.
The heart is the source of evil plots with deceit (14). The heart is the wellspring of life (4:23). Jesus said, “Out of the heart comes all kinds of evil.” The remedy to a deceitful heart is to allow the word of God and his Spirit to sink into my heart. (Matthew 13:19-23) Then I will be able to produce fruit that pleases my father.