來者不善，善者不來

来者不善，善者不来
láizhěbùshàn,shànzhěbùlái
  1. He who comes is surely ill-intentioned, no-one well-meaning will come (idiom).
  2. Be careful not to trust foreigners.
  3. Beware of Greeks bearing gifts!

CEDICT

Entry Composition

1 來者 láizhě
  1. (archaic) one coming to pay homage; submitter
  2. (archaic) the following; the next in sequence; follow-up
  3. (literary) future generations
  4. (literary) the future; future events
  5. Used other than figuratively or idiomatically: see 來 /来 (lái), 者 (zhě).
  6. future generations
  7. one coming to pay homage; submitter
  8. the following; the next in sequence; follow-up
  9. the future; future events
2 不善 bùshàn
  1. bad
  2. ill
  3. not good at
  4. not to be pooh-poohed
  5. quite impressive
3 善 shàn
  1. good (virtuous)
  2. benevolent
  3. well-disposed
  4. good at sth
  5. to improve or perfect
4 者 zhě
  1. (after a verb or adjective) one who (is) ...
  2. (after a noun) person involved in ...
  3. -er
  4. -ist
  5. (used after a number or 後 hòu or 前 qián to refer to sth mentioned previously)
  6. (used after a term, to mark a pause before defining the term)
  7. (old) (used at the end of a command)
  8. (old) this
5 不來 bùlái
  1. (as a complement) be unable to
  2. be unable to
  3. to not come