A liar is not believed even if he tells the truth.
More Hungarian Proverbs:
His words are nice but he is a devil.Hungarian
It is easy to inflict a wound, but difficult to heal it.
Hungarian
One cannot sit in two saddles having one arse/bottom only.
Hungarian
As one makes his bed, so he sleeps his dream.
Hungarian
He is between two fires.
Hungarian
He who digs a pit for the horse of another man, will find his own horse's neck broken there.
Hungarian