Mencius. Book 4, Part 1, Chapter 13.
Book 4, Le Low. Part 1.
1. Mencius said, "Pih-e, that he might avoid Chow, was dwelling on the coast of the northern sea. When he heard of the rise of King Wan, he roused himself, and said, 'Why should I not go and follow him? I have heard that the chief of the west knows well how to nourish the old.' T'ae-kung, that he might avoid Chow, was dwelling on the coast of the eastern sea. When he heard of the rise of King Wan, he roused himself, and said, 'Why should I not go and follow him? I have heard that the chief of the west knows well how to nourish the old.'
2. "Those two old men were the greatest old men of the empire. When they came to follow King Wan, it was the fathers of the empire coming to follow him. When the fathers of the empire joined him, how could the sons go to any others?
3. "Were any of the princes to practice the government of King Wan, within seven years, he would be sure to be giving laws to the empire."
Text source: The Works of Mencius. Translated by James Legge.