The Discourse of Loving Kindness in Sutta Nipata

What should be done by one who's skilled in wholesomeness
To gain the state of peacefulness is this:
One must be able, upright, straight and not proud,
Easy to speak to, mild and well content,
Easily satisfied and not caught up
In too much bustle, and frugal in one's ways,
With senses calmed, intelligent, not bold,
Not being covetous when with other folk,
Abstaining from the ways the wise ones blame,
And this the thought one should always hold:
'May beings all live happy and safe
And may their hearts rejoice within themselves.
Whatever there may be with breath in life,
Whether they be frail or very strong,
Without exception, by they long or very short
Or middle-sized, or be they big or small,
Or thick, or visible, or invisible,
Or whether they dwell far or they dwell near,
Those that are here, those seeking to exist --
May beings all rejoice within themselves.
Let no one bring about another's ruin,
And not despise in any way or place,
Let not them wish each other any ill
From provocation or form enmity.
Just as a mother at the risk of life
Love and protects her child, her only child,
So one should cultivate this boundless love,
To all that live in the whole universe
Extending from a consciousness sublime
Upwards and downwards and across the world
Untroubled, free from hate and enmity,
And while one stands and while one walks and sits
Or one lies down still free of drowiness
One should be intent on this mindfulness -- 
This is the divine abiding here they say.
But when one lives quite free of any view,
Is virtuous, with perfect insight won,
And greed for sensual desires expelled,
One surely comes no more to any womb.

-The Buddha's Words in Sutta Nipata