Baha'i
Blessed is he who preferreth his brother before him.
[Baha'u'llah Tablets]

Buddhism
Hurt not others in ways that you yourself would find hurtful.
[Udana-Varga 5,18]  

Christianity
Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law of the prophets.
[Matthew 7:12]  

 Christian 
"Love the Lord your God with all your heart and mind and strength. The second is this: Love your neighbor as yourself.  There is no commandment greater than these."
[Mark 12: 30-31 NIV]

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

 Hindu
Whoso looks upon all beings in the same way as himself and sees likeness in all, he is deemed the supreme yogin. 
[The Bhagavad-Gita, Chapter 6:32]

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

 Jain
A man should treat all creatures in the world as he himself would like to be treated.
[The Jain Spiritual Tradition]

 Judaism
What is hateful to you, do not to your fellowmen.
That is the entire Law; all the rest is commentary.
[Talmud Shabbat 31a]

 Native
Peace is at the heart of everything and is shown in the sharing and caring of nature and all people.
[Native Spiritual Tradition]

 Sikh
The worldly way is to return good for good, but the Guru's way is to return good for evil.
[Bhai Gurdas, Var 28:11:6]

 Taoism
Regard your neighbor's gain as your own gain and your neighbor's loss as your own loss.
[T'ai Shang Kan Ying P'ien]

 The Process
As you give, so shall you receive

 Unitarian
We covenant to affirm the worth and dignity of every person.
[Principles of the Unitarian Church]
 

 Wicca
An' it harm none, do as ye will.
[Rede]

 Zoroastrianism
That nature alone is good which refrains from doing unto another whatsoever is not good for itself.
[Dadistan-i-dinik 94-5]

 And... George Bernard Shaw
Do not do unto others as you would that they should do unto you.
Their tastes may not be the same.
[1903]