好事不出门，恶事传千里

好事不出門，惡事傳千里
hǎoshìbùchūmén,èshìchuánqiānlǐ
  1. lit. good deeds do not go beyond the door, evil deeds spread a thousand miles
  2. a good deed goes unnoticed, but scandal spreads fast (idiom)

CEDICT

Entry Composition

1 好事 hǎoshì
  1. good action, deed, thing or work (also sarcastic, "a fine thing indeed")
  2. charity
  3. happy occasion
  4. Daoist or Buddhist ceremony for the souls of the dead
2 不出 bùchū to not exceed; to not surpass
3 门 mén
  1. gate
  2. door
  3. gateway
  4. doorway
  5. opening
  6. valve
  7. switch
  8. way to do something
  9. knack
  10. family
  11. house
  12. (religious) sect
  13. school (of thought)
  14. class
  15. category
  16. phylum or division (taxonomy)
  17. classifier for large guns
  18. classifier for lessons, subjects, branches of technology
  19. (suffix) -gate (i.e. scandal; derived from Watergate)

classifiers: 扇, 個
4 恶事传千里 èshìchuánqiānlǐ evil deeds spread a thousand miles (idiom); scandal spreads like wildfire