When we have an evil mind, our thoughts and actions become evil. On the other hand, when we have good mind, we can do everything in goodness. When he was rebuked by Jesus, Peter, one of disciples of Jesus, didn't have ill feeling but loved Him with an unchanging heart. So he could change himself, and later received amazing power from God. With that power he could heal many sick people and he guided thousands of people to repentance a day. In this manner, whoever thinks, talks, and acts with good heart can bear good fruit abundantly in the power of God.
"For there is no good tree which produces bad fruit, nor, on the other hand, a bad tree which produces good fruit" (Luke 6:43).