Confucius. Book 4, Chapter 13.
Book 4, Le Jin.
The Master said, "Is [if??] a prince able to govern his kingdom with the complaisance proper to the rules of propriety, what difficuly will he have? If he cannot govern it with that complaisance, what has he to do with the rules of propriety?"
Text source: Lun Yu, The Confucian Analects. Translated by James Legge.