心上有杆秤

Traditional (Taiwan): 心上有桿秤

xīnshangyǒugǎnchèng ㄒㄧㄣ ˙ㄕㄤ ㄧㄡˇ ㄍㄢˇ ㄔㄥˋ

    • to be able to tell right from wrong and good from bad

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
a steyard scale in the heart
Meaning
Having the ability to tell right from wrong and good from bad. Approving.

Sources