Proverbs 17:12 NASB - "Let a man meet a bear robbed of her cubs, Rather than a fool in his folly."
This Proverb effectively uses a word picture because everybody knows a mama bear is fiercely protective of her cubs and that it is unwise to cross her path when she's worried about her cub(s). Far fewer people think of fools as being as dangerous as an angry mama bear. However, the Bible warns us that fools are more dangerous than angry bears.
Be careful whose path you cross.