My friends are my estate. Forgive me then the avarice to hoard them.
Emily Dickinson
The proper office of a friend is to side with you when you are in the wrong. Nearly anybody will side with you when you are in the right...
Mark Twain
The only reward of virtue is virtue; the only way to have a friend is to be one.
Ralph Waldo Emerson
Hold a true friend with both your hands.
Friedrich Nietzsche
Tell me what company you keep, and I'll tell you what you are.
Miguel de Cervantes