speak with a forked tongue
To lie; to say one thing while thinking of the opposite.
Лгать; быть лжецом, лицемерным человеком.
I have learned not to trust Peter's promises because he speaks with a forked tongue.
This man is always speaking with a forked tongue and nobody trusts him.
Этот мужчина всегда лжет и ему никто не доверяет.