以小人之心，度君子之腹
yǐ​xiǎo​rén​zhī​xīn​duó​jūn​zǐ​zhī​fù

to judge a noble person with a mean mind

以小人之心，度君子之腹 yǐ​xiǎo​rén​zhī​xīn​duó​jūn​zǐ​zhī​fù
to judge a noble person with a mean mind
to gauge the heart of a gentleman with one's own mean measure; to use narrow-minded thinking to guess the motives of a person with high integrity