Related:

• Even a fool who keeps silent is considered wise; when he closes his lips, he is deemed intelligent.
  -- Proverbs 17:28...
• The eyes of a fool are in the ends of the earth. -- Old Testament -- Proverbs xvii, 24
• He that hath knowledge spareth his words. -- Old Testament -- Proverbs xvii, 27
• Answer a fool according to his folly. -- Old Testament -- Proverbs xxvi, 5
• As a dog returns to his vomit, so a fool returneth to his folly.
  Seest thou a man wise in his own conceit? There is more hope of a fool than of him....
• He that repeateth a matter separateth very friends. -- Old Testament -- Proverbs xvii, 9
• It is naught, it is naught, saith the buyer; but when he is gone his way, then he boasteth.
  -- Old Testament -- Proverbs xx, 14...
• Remove not the ancient landmark. -- Old Testament -- Proverbs xxii, 28; xxiii, 10