'Foolishness' in the Bible

A prudent man keeps what he knows to himself, but the hearts of fools shout forth their foolishness.

The wise speak, presenting knowledge appropriately, but fools spout foolishness.

Anyone who has understanding is a fountain of life, but foolishness brings punishment to fools.

A man's foolishness ruins his life, yet his heart rages against the LORD.

Don't answer a fool according to his foolishness, or you will be just like him.

Answer a fool according to his foolishness, or he will think himself to be wise.