The disciples of Gotama are always well awake, and their mind day and night always delights in compassion.
Suppabuddhaṁ pabujjhanti, sadā gotamasāvakā; Yesaṁ divā ca ratto ca, ahiṁsāya rato mano.
Dhammapada 300
The same idea in other traditions
We sent thee not, but as a Mercy for all creatures.
Blessed are the merciful: for they shall obtain mercy.
And a stranger shalt thou not oppress; for ye know the heart of a stranger, seeing ye were strangers in the land of Egypt.
By renouncing pleasures he obtains freedom from false longing, whereby he becomes compassionate, humble, free from sorrow, …
One who does not frighten anyone, and who is not afraid of anyone else - says Nanak, listen, mind: call him spiritually wise.
He through whom the world is not agitated, and who is not agitated by the world, who is free from joy and anger and fear and agitation, he too is dear to me.
Mencius said, 'All men have a mind which cannot bear to see the sufferings of others. … even now-a-days, if men suddenly see a child about to fall into a well, they will without exception experience a feeling of alarm and distress. … The feeling of commiseration is the principle of benevolence. …
In a desert a man found a dog that was dying from thirst. Using his hat as a bucket, he fetched water from a well and gave it to the helpless animal. The prophet of the time stated that God had forgiven the man his sins because of his kindly act. Reflect, if thou be a tyrant, and make a profession of benevolence. He who shows kindness to a dog will not do less towards the good among his fellows. …