Confucius. Book 3, Chapter 21.
Book 3, Pa Yih.
1. The duke Ai asked Tsai Wo about the altars of the spirits of the land. Tsai Wo replied, "The Hsia sovereign planted the pine tree about them; the men of the Yin planted the cypress; and the men of the Chou planted the chestnut tree, meaning thereby to cause the people to be in awe."
2. When the Master heard it, he said, "Things that are done, it is needless to speak about; things that have had their course, it is needless to remonstrate about; things that are past, it is needless to blame."
Text source: Lun Yu, The Confucian Analects. Translated by James Legge.