You brood of vipers! How can you speak good, when you are evil? For out of the abundance of the heart the mouth speaks.
34. Offspring of vipers. The similarity between the tree and the fruit is here applied by Christ to nothing more than speech, because this afforded an opportunity of detecting the inward and concealed malice of the scribes; and that is the reason why he dwells so much on this one kind of sin.
Satan blinds the eye of faith and seals up the lips of prayer; a soul under his power sees nothing and says nothing to the purpose. But Christ's mercy is directly opposite to Satan's malice. When Satan's power breaks, the eyes open to see God's glory and the lips open to speak His praise.
AI summary
Commenting on Matthew 12:22-37
But he answered and said unto them,.... Not to the Pharisees, who were unworthy of an answer from him; having, in such an imperious manner, and with a sole view to tempt him, and after such miracles were wrought by him, required of him a sign from heaven; but to the multitude, the throng of people gathered thick together on this occasion, see Mat 12:45...