The tongue speaks, but the head doesn’t know.
More Russian Proverbs:
Having given your word, be strong; not having done it, try not to promise.Russian
God does not give to the cow that butts.
Russian
Sorrow doesn't kill, but it blights.
Russian
A drop of water in the eyes of the Tsar costs the country many handkerchiefs.
Russian
A woman's tongue is longer than her hair.
Russian
One does not regret giving one's own ear-ring to one's dear friend.
Russian