鐵打的衙門，流水的官 [铁－－－门－－－－－]

Jyutping
Pinyin tiě dǎ de yá men , liú shuǐ de guān

Definitions (CC-CEDICT)
  1. lit. the yamen is strong as iron, the officials flow like water (idiom)
  2. fig. government officials come and go