Wisdom of the Bodhisattva's Way by Shantideva.

“If I give this, what will be left for me?”
Thinking of oneself – the way of evil ghosts.
“If I keep this, what will be left to give?”
Concern for others is the way of heaven.

If I serve myself and harm another,
I'll suffer in the realms of hell.
But if for others' sake I harm myself,
Then every excellence will be my heritage.

Wanting what is best for me –
Stupidity, inferiority, and lower realms result!
Let this be changed, applied to others –
Honors and the realms of bliss will come!

Enslaving others, forcing them to serve me,
I will come to know the state of servitude.
But if I labor for the good of others,
Mastery and leadership will come to me.

All the joy the world contains
Has come through wishing happiness for others.
All the mysery the world contains
Has come through wanting pleasure for oneself.

Shantideva, The Way of the Bodhisattva