One should not behave towards others in a way which is disagreeable to oneself. This is the essence of morality. All other activities are due to selfish desire. (Mahabharata, Anusasana Parva 113.8 - Hinduism)
Comparing oneself to others in such terms as "Just as I am so are they, just as they are so am I," he should neither kill nor cause others to kill.
(Sutta Nipata 705 - Buddhism)
The sage has no interest of his own, but takes the interests of the people as his own. He is kind to the kind; he is also kind to the unkind: for Virtue is kind. He is faithful to the faithful; he is also faithful to the unfaithful: for Virtue is faithful. (Tao Te Ching, Chapter 49 - Taoism)
Whatever you wish that men would do to you, do so to them.
(7:12, Matthew - Bible)
...And do good unto your parents, and near of kin, and unto orphans, and the needy, and the neighbour from among your own people, and the neighbour who is a stranger, and the friend by your side, and the wayfarer, and those whom you rightfully possess... (Quran 4:36 - Islam)