In Matthew’s gospel, fruit is used in reference to actions (Matthew 3:3; Matthew 23:3) and teaching (Matthew 12:22–37; Matthew 24:4–5, Matthew 24:11–12, Matthew 24:24–26). Presumably, false prophets will be recognized as such when they live in a way that is at odds with what Jesus has commanded (Matthew 5:21–7:12) and teach doctrine that contradicts the doctrine taught by Jesus.1
16 You will recognize them by their fruits. Are grapes gathered from thornbushes, or figs from thistles?