Full Idea
Let us consider if a traitor, who would sell his own country to us, may not often be as advantageous to us, as an hero who defends us: and yet we can love the treason, and hate the traitor.
Gist of Idea
We dislike a traitor, even if they give us great benefit
Source
Francis Hutcheson (Treatise 2: Virtue or Moral Good [1725], §I.VI)
Book Reference
'British Moralists 1650-1800 Vol. 1', ed/tr. Raphael,D.D. [Hackett 1991], p.267
A Reaction
A nice example, which certainly refutes any claim that morality is entirely and directly self-interested. High-minded idealism, though, is not the only alternative explanation. We admire loyalty, but not loyalty to, say, Hitler.