Full Idea
A man who is only susceptible of friendship, without public spirit or a regard to the community, is deficient in the most material part of virtue.
Gist of Idea
Friendship without community spirit misses out on the main part of virtue
Source
David Hume (That Politics may be reduced to a Science [1750], p.21)
A Reaction
I think this is aimed at the epicureans. If the highest virtues are focused on one's friends that can easily lead to injustice, because it can tolerate prejudice against people who are very unlike one's friends.
Book Reference
Hume,David: 'Selected Essays' [OUP 1996], p.21