wǎng​jǐ​zhèng​rén

preach rectitude while being dishonest

枉己正人 wǎng​jǐ​zhèng​rén
preach rectitude while being dishonest
To try to reform or correct others despite one's own behavior being improper or dishonest; based on a passage in Mencius stating that one cannot straighten others by being crooked oneself