Summary:

There are many wolves that carry captive those that are running towards God (IGNATIUS).

He who inquires of a false prophet in regard to any action is an idolater, and devoid of the truth, and foolish (HERMAS).

There are, therefore, and there were many, who, coming forward in the name of Jesus, taught both to speak and act impious and blasphemous things (JUSTIN MARTYR).

False Christs, false prophets, and false apostles have come to split up the one Church into parts through their corrupting doctrines (HEGESIPPUS). 

There are those who inwardly are wolves, yet wear sheep's clothing in the eyes of the world (IRENAEUS).

For the false prophets possessed the prophetic name dishonestly, being prophets, but prophets of the liar (CLEMENT OF ALEXANDRIA).

One who sets forth in detail things yet to be, was rightly judged a prophet (HIPPOLYTUS).

  

What are these sheep’s clothing, but the external surface of the Christian profession? Who are the ravening wolves but those deceitful senses and spirits which are lurking within to waste the flock of Christ? Who are the false prophets but deceptive predictors of the future? (TERTULLIAN).

Therefore from their ways shall the false prophet and the prophet be known (THE DIDACHE).

Converting into unholy persons, manifests them to be enemies of God and false prophets (DIONYSIUS OF ALEXANDRIA).

The tree is made manifest by its fruit; so those that profess themselves to be Christ’s are known not only by what they say, but by what they practice (IGNATIUS).

For the fruits of the prophet must needs be brought to the test: for “from its fruit is the tree known” (APOLLONIUS).

It may be called a good tree if, through its power of choice, it appoints good things; or it may be called evil if it should choose evil things (ORIGEN).

A man is unfruitful when he is carnal (HIPPOLYTUS).

An honest mind and good faith cannot produce evil deeds, any more than an evil disposition can produce good deeds (TERTULLIAN).

If, however, a tree continues alone, not producing fruit fully formed, it is utterly destroyed (HIPPOLYTUS).