Hurt not others in ways
that you yourself
would find hurtful
Buddhism

What is hateful to you,
do not to your fellow man.
That is the entire Law;
all the rest is commentary. 
Judaism

Do unto others
as you would have them
do unto you.
  Christianity

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

Blessed is he
who preferreth his brother
before himself
Baha’i Faith