Full Idea
To tell the truth for the sake of duty is something entirely different from doing so out of concern for inconvenient results.
Gist of Idea
Telling the truth from duty is quite different from doing so to avoid inconvenience
Source
Immanuel Kant (Groundwork of the Metaphysic of Morals [1785], 402.18)
Book Reference
Kant,Immanuel: 'The Moral Law (Groundwork of Morals)', ed/tr. Paton,H.J. [Hutchinson 1948], p.68