Confucius. Book 3, Chapter 2.
Book 3, Pa Yih.
The three families used the Yung ode, while the vessels were being removed, at the conclusion of the sacrifice. The Master said," 'Assisting are the princes; ‹ the son of heaven looks profound and grave'; ‹ what application can these words have in the hall of the three families?"
Text source: Lun Yu, The Confucian Analects. Translated by James Legge.