'Fool' in the Bible

And the king lamented over Abner, and said, Died Abner as a fool dieth?

When David went home to pronounce a blessing on his own house, Michal, Saul's daughter, came out to meet him. She said, "How the king of Israel has distinguished himself this day! He has exposed himself today before his servants' slave girls the way a vulgar fool might do!"

With the pure, you show yourself pure, but with the crooked, you appear as a fool.