(Extrapolated from the Sitting Dhyana Samadhi Sutra)
For beginners, start by being kind to those you care about. Make the wishes of your dearly beloved come true. Make them happy physically, psychically and spiritually by providing them with material gifts, for example. Practitioners focus on kind thoughts without veering.
For more advanced practitioners, practice being kind to those whom you feel neutral. Focus on providing others with happiness. When the mind wanders off to other things, gently pull it back to kind thoughts.
For the most advanced practitioners, be kind to those you hate. Bestow happiness on your enemies the way you would upon your dearly beloved. Focus on kind thoughts and your heart will open up and become pure. You will see that all beings everywhere are just like you, an insight that makes anyone happy.
How can we be empathetic toward, and furthermore wish happiness upon, people who are evil though? Everyone has an aspect of good in them. Why should we ignore and drown out their goodness over one incident? The people we resent now may be people we loved dearly some time past; they may have been our family or friends in lives past. How could we hate them and heap more resentment upon them now? We will be patient with them and consider them our benefactors. Without hateful people and situations, how can we develop patience? People we resent help us grow our patience. Remember the humaneness and virtue of this practice, the splendid power of kindness is never lost.
Hatred is like venom; it is difficult to contain. When we wish to burn others, we are really hurting ourselves. The number of pebbles on the road is countless, like hatred they cannot be eliminated with covered leather everywhere we walk; instead, we could guard against them by wearing the sandals of patience.
Don the shield of great kindness to shelter against the arrows of affliction. Kindness is the medicine that absolves resentment and loosens the knot of venom. When worries burn the mind, kindness can extinguish them. Kindness is the ladder that allows us to climb onto the platform of ease. Kindness is the boat that allows us to cross the sea of cyclical birth and death. Among all valuables, kindness is one dazzling gem. On the journey to enlightenment, kindness is sustenance.
The most admirable figures in history consider it a joy to regard all humankind with kindness, so I shall do the same.