He cannot be a friend to any one who is his own enemy.
More French Proverbs:
A woman's tongue is her sword, and she does not let it rust.French
The coalheaver is master at home.
French
There are no miracles for those that have no faith in them.
French
No wind can do him good who steers for no port.
French
It is a double pleasure to deceive the deceiver.
French
Not every dog that barks bites.
French