The reward of friendship is ...

The reward of friendship is itself. The man who hopes for anything else does not understand what true friendship is.
 Aelred of Rievaulx

Quotes from the same author

No medicine is more valuable , none more efficacious, none better suited to the cure of our temporal ills than a friend to whom we may turn for consolation in time of trouble, and with whom we may share happiness in time of joy.
 Aelred of Rievaulx
Friendship is that virtue by which spirits are bound by ties of love and sweetness and out of many are made one.
 Aelred of Rievaulx