識良莠

Simplified: 识良莠

shíliángyǒu ㄕˊ ㄌㄧㄤˊ ㄧㄡˇ

    • to tell good people from bad

Character by character

Saying俗语俗語

Idiom惯用语 · Rarely used now

Literally
tell good grain from weeds
Meaning
To distinguish good people from bad. 莠 is a weed that looks like millet.

Sources