John Chrysostom
Catena Aurea · Matthäusevangelium 12
Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit. O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh. A good man out of the good treasure of the heart bringeth forth good things: and an evil man out of the evil treasure bringeth forth evil things.
For the discerning of a tree is done by its fruits, not the fruits by the tree. A tree is known by its fruits. For though the tree is the cause of the fruit, yet the fruit is the evidence of the tree. But ye do the very contrary, having no fault to allege against the works, ye pass a sentence of evil against the tree, saying that I have a dæmon.