口是心苗

kǒushìxīnmiáo ㄎㄡˇ ㄕˋ ㄒㄧㄣ ㄇㄧㄠˊ

    • what one says reveals what one thinks

Character by character

Saying俗语俗語

Proverb谚语諺語 · Rarely used now

Literally
the mouth is the sprout of the heart
Meaning
What a person says reveals what they think.

Sources