Like a lame man's legs, which hang useless, is a proverb in the mouth of fools.
Proverbs 26:7 ESV

A fool doesn't understand the meaning or application of a proverb. He uses it to mock or bludgeon or to make himself look wise without doing any of the work required to gain real wisdom. If people listen to his advice, he's more likely to do harm with the best intentions.