The Magna Moralia or Great Ethics is a treatise traditionally attributed to Aristotle, but now more often thought to be by a later writer in the Aristotelian tradition.
Free online texts
Internet Archive: The Works of Aristotle - Magna Moralia, Ethica Eudemia, De Virtutibus Et Vitiis. English translations, edited by W.D. Ross (1915). Multiple formats.
Wikisource: Ηθικά Μεγάλα, Greek text.
Librivox: Magna Moralia, public domain audiobook.
Wikipedia: Magna Moralia.
The Great Conversation: Further reading at Tom's Learning Notes
Aristotle: Nicomachean Ethics.
Aristotle: Eudemian Ethics.
Ancient Greek resources: Learn to read Greek classics in the original.