Mencius - Book 4, Part 1, Chapter 12

Mencius said, 'When those occupying inferior situations do not obtain the confidence of the sovereign, they cannot succeed in governing the people. There is a way to obtain the confidence of the sovereign: if one is not trusted by his friends, he will not obtain the confidence of his sovereign. There is a way of being trusted by one's friends: if one do not serve his parents so as to make them pleased, he will not be trusted by his friends. There is a way to make one's parents pleased: if one, on turning his thoughts inwards, finds a want of sincerity, he will not give pleasure to his parents. There is a way to the attainment of sincerity in one's self: if a man do not understand what is good, he will not attain sincerity in himself.

'Therefore, sincerity is the way of Heaven. To think how to be sincere is the way of man.

Never has there been one possessed of complete sincerity, who did not move others. Never has there been one who had not sincerity who was able to move others.'
~ James Legge translation via nothingistic.org ~

Go here to read the introductory post to this serialized version of the Works of Mencius.