Matthew 12:34

Verses 34,35. O generation of vipers. Christ here applies the argument which he had suggested in the previous verse. They were a wicked race; like poisonous reptiles, with a corrupt and evil nature. They could not be expected to speak good things--that is, to speak favourably of him and his works. As the bad fruit of a tree was the proper effect of its nature, so were their words about him and his works the proper effects of their nature. The abundance or fulness of the heart produced the words of the lips. Vipers. These are a poisonous kind of serpents, not often a yard long, and about an inch thick, having a flat head.