Watch out for the dog that doesn’t bark and the man who says nothing.
More Spanish Proverbs:
Copper begets copper, and not (the labour of) men's bones.Spanish
The lean dog is all fleas.
Spanish
He that would have a beautiful wife should choose her on a Sunday.
Spanish
Whether you boil snow or pound it you can have but water of it.
Spanish
Paper and ink and little justice.
Spanish
He who does not show himself, is overlooked.
Spanish