十年磨一劍 [－－－－剑]

Jyutping sap6 nin4 mo4 jat1 gim3
Pinyin shí nián mó yī jiàn

Definitions (粵典–words.hk)
  1. 語句
    比喻​長​時間​努力​先​有所​成就
    success or achievement after long time devotement; literally: ten years to sharpen one single sword