Beware of silent dogs and still waters.
More Portuguese Proverbs:
Grief for a dead wife lasts to the door.Portuguese
A good word quenches more than a cauldron of water.
Portuguese
He that would be old long must begin betimes.
Portuguese
The chicken that stays in the farmyard, will peck the crumbs.
Portuguese
He keeps his road well enough who gets rid of bad company.
Portuguese
You have to suffer a lot or die young.
Portuguese