"Tsze-kung said, What I do not wish men to do to me, I also wish not to do to men. The Master said, Tsze, you have not attained to that."
Confucius (551-479 BC), Analects 5:12
"Tzu-kung asked, Is there a single word which can be a guide to conduct throughout one's life? The Master said, It is perhaps the word shu [reciprocity]. What you don't want yourself, don't do to others."
Confucius (551-479 BC), Analects 15:23-24
"When one cultivates to the utmost the principles of his nature, and exercises them on the principle of reciprocity, he is not far from the path. What you do not like when done to yourself, do not do to others."