Common Ground
Author unknown, sourced via internet

Hurt not others in ways you yourself would find hurtful
Udana-Vearga, 5,18 (Bhuddism)

This is the sum of duty: Do naught unto others which would cause pain if done to you
Mahabharata 5, 1517 (Brahmanism)

Therefore whatsoever ye would that men should do to you, do you even so unto them
Matthew 7:12 (Christianity)

Surely it is the maxim of loving kindness: Do not unto others that you would not have them do unto you
Analects 15,23 (Confucianism)

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

What is hateful to you do not do to your fellowmen.  That is the entire law; all the rest is commentary
Talmud Shabbat 31a (Judiasm)

Regard your neighbor's gain as your own gain, and your neighbor's loss as your own loss
T'ai Shang Kam Ying P'ien (Taoism)

That nature alone is good that refrains from doing unto another whatsoever is not good for itself
Dadistan-i-dinik 94,5 (Zoroastrianism)

The spear in the Other's heart is the spear in Your Own; You are He. There is no other wisdom, and no other hope for us but that we grow wise
Surak (IDIC)

An it harm none, do what thou will
The Wiccan Rede

Be excellent to each other
Bill & Ted