捫心自問 [扪－－问]

Jyutping mun4 sam1 zi6 man6
Pinyin mén xīn zì wèn

Definitions (CC-CEDICT)
  1. to ask oneself honestly
  2. to search in one's heart
Definitions (粵典–words.hk)
  1. x
Definitions (Wiktionary)
  1. phrase, idiomatic
    lay the hand on the heart and examine oneself