The firmest friendships have been formed in mutual adversity, as iron is most strongly united by the fiercest flame.
Colton
Only that soul can be my friend which I encounter on the line of my own march, that soul to which I do not decline and which does not decline to me, but, native of the same celestial latitude, repeats in its own all my experience.
Emerson
Culture of Friendship
It is a friendly heart that has plenty of friends.
Thackeray