Matthew 12:34

Generation of vipers. Or, “offspring of vipers” (see on ch. 3:7).

How can ye? The “fruit” (v. 33), or the “offspring” (v. 34), of the Pharisees was not “good.” The “things” they had spoken — their “fruit” — was “evil,” and this in turn pointed to an evil source. They acted like “vipers,” and it must therefore be that they were the offspring of “vipers” (see on John 8:44).

Abundance of the heart. A man’s words are to a greater or lesser extent a reflection of the thoughts that fill his mind; it cannot be otherwise. The blasphemous words of the Pharisees (v. 24) were not accidental, but represented what was in their hearts. A man’s words betray his thoughts.