The universality of morality

Confucianism - Do not do to others what you would not
 like yourself. Then there will be no resentment
 against you, either in the family or in the state.
 Analects 12:2

Buddhism - Hurt not others in ways that you yourself
 would find hurtful. Udana-Varga 5,1

Christianity - All things whatsoever ye would that men
 should do to you, do ye so to them; for this
 is the law and the prophets. Matthew 7:1

Hinduism - This is the sum of duty; do naught onto others
 what you would not have them do unto you.
 Mahabharata 5,1517

Islam - No one of you is a believer until he desires for
 his brother that which he desires for himself.
 Sunnah

Judaism - What is hateful to you, do not do to your
 fellowman. This is the entire Law; all the
 rest is commentary. Talmud, Shabbat 3id

Taoism - Regard your neighbor's gain as your gain, and
 your neighbor's loss as your own loss.
 Tai Shang Kan Yin P'ien

Zoroastrianism - That nature alone is good which refrains
 from doing another whatsoever is not good for itself.
 Dadisten-I-dinik, 94,5

It doesn't really matter what book you read, what God you call Father (or mother), what language you chant your prayers or meditations in, "Do unto others as you would have them do unto you, and do not unto others that which you would not have done to you." Seems to be a good general rule ... EVERYONE seems to say it at one time or another :). Thanks to Apollo from PVP for the quotes :)