防民之口，甚於防川 [－－－－－－于－－]

Jyutping fong4 man4 zi1 hau2 ， sam6 jyu1 fong4 cyun1
Pinyin fáng mín zhī kǒu ， shèn yú fáng chuān

Definitions (Wiktionary)
  1. phrase, idiomatic
    It is more sinister and ominous to stop civilians from speaking than to block the river flows.