To enjoy and to give joy, without harming either oneself or anyone else, that, I think, is all of morality.

[Jouis et fair jouir, sans faire mal ni à toi ni à personne, voilà, je crois, toute la morale.]

Nicolas Chamfort (1741-1794) French writer, epigrammist (b. Nicolas-Sébastien Roch)

Products of Perfected Civilization [Produits de la Civilisation Perfectionée], Part 1 “Maxims and Thoughts [Maximes et Pensées],” ch. 5, ¶ 319 (1795) [tr. Siniscalchi (1994)]
    (Source)

(Source (French)). Alternate translations:

To enjoy yourself and make others enjoy themselves, without harming yourself or any other; that, to my mind, is the whole of ethics.
[tr. Mathers (1926)]

Enjoy and give pleasure, without doing harm to yourself or to anyone else -- that, I think, is the whole of morality.
[tr. Merwin (1969)]

Enjoy and make others enjoy; without doing harm to yourself or anyone else: that, I think, sums up the whole of morality.
[tr. Pearson (1973)]

Give and take pleasure, without doing harm to yourself or anyone else -- that, I think, sums up morality.
[tr. Dusinberre (1992), Frag. 319]

Take your pleasure, give pleasure to others without doing harm to yourself or to anyone else: that sums up the whole of morality.
[tr. Parmée (2003), ¶ 196]