受人之託，忠人之事 [－－－托－－－－－]

Jyutping sau6 jan4 zi1 tok3 ， zung1 jan4 zi1 si6
Pinyin shòu rén zhī tuō ， zhōng rén zhī shì

Definitions (Wiktionary)
  1. proverb
    If a friend asks for a favor, you should do your utmost to help.