Tā zhège rén xīnkǒu-bùyī, shuō de huà bù néng quán xìn.
He says one thing and thinks another, so you can't believe everything he says.
Tips
usage
Milder than 口是心非. 口是心非 is deliberate two-facedness, while 心口不一 covers any gap between words and feelings, including polite white lies and inner conflict. The opposite is 心口如一, saying what one thinks.
