expression
words betray one's character
Proverb meaning that the way a person speaks reveals their true nature, education, or upbringing.
彼の丁寧な話し方を聞いて、言葉は身の文だと思った。
Hearing his polite way of speaking, I thought that words truly reveal one's character.
A traditional Japanese proverb. The exact origin is uncertain, but it reflects the cultural belief that speech reflects inner character.