流水不腐，戶樞不蠹 [－－－－－户枢－－]

Jyutping lau4 seoi2 bat1 fu6 ， wu6 syu1 bat1 dou3
Pinyin liú shuǐ bù fǔ ， hù shū bù dù

Definitions (Wiktionary)
  1. phrase, idiomatic
    Flowing water is never stale and a moving door hinge never gets rusty
  2. phrase, figuratively, idiomatic
    Things in frequent use are not easily eroded, and can remain energetic.
  3. phrase, figuratively, idiomatic
    A rolling stone gathers no moss

流水不腐，戶樞不蠹 [－－－－－户枢－－]

Jyutping lau4 seoi2 bat1 fu6 , wu6 syu1 bat1 dou3
Pinyin liú shuǐ bù fǔ , hù shū bù dù

Definitions (CC-CEDICT)
  1. lit. flowing water does not rot, nor a door-hinge rust (idiom)
  2. fig. constant activity prevents decay