Extracted from the website of Buddhist Vajrayana Charity Funds Association and translated
(四無量心) into English:

The Four Immeasurable Hearts

‘Benevolence’	－	is to give benefit, peace and happiness to sentient beings.
‘Compassion’	－	is to relieve the suffering of sentient beings, to liberate sentient beings from birth-death (the fundamental problem of sentient beings).

‘Joy’

－

is be joyful by seeing sentient beings abandoning suffering and obtaining happiness.  The happiness of sentient beings is like one's own happiness.

‘Renunciation’	－	is to treat enemies and friends equally.  Not to remember how sentient beings have treated us in favour or resentment, hence differentiating love and hate.

The Four Immeasurable Hearts: Benevolence, Compassion, Joy, Renunciation are the innermost essence of various Buddhas and Bodhisattvas; with the mission being to benefit and set free all sentient beings. What are the Four Immeasurable Hearts?

《Verses on the Treasury of Abhidharma》(Fasc.29)says： How can one enable all sentient beings to have such happiness?  In case of such thinking, one attains Benevolence. How can one enable all sentient beings to be free from suffering?  In case of such thinking, one attains Compassion. All those sentient beings receive happiness and are free from sufferings, wouldn’t it be a pleasure!  In case of such thinking, one attains Joy. All those sentient beings are treated equally and fairly, with no difference in affection or enmity.  In case of such thinking, one attains Renunciation.

Buddhas and Bodhisattvas generate the Four Immeasurable Hearts because of sentient beings; the Bodhi is nurtured because of the Four Immeasurable Hearts; the Buddha Path is attained because of Bodhi.  From this, one should notice that before one’s arousal of intention to have Bodhicitta, one must first initiate the Hearts of Benevolence, Compassion, Joy and Renunciation.

【Dafangguang Fohuayan Jing】‘The Aspiration of Samantabhadra Bodhisattva’ states: Various Buddha Tathagata regard the Great Compassionate Heart as the core system.  This is because Great Compassion is generated by contemplating the suffering of all sentient beings; Bodhicitta comes from Great Compassion and the Enlightenment is accomplished by completing Bodhicitta.

《Verses on the Essence of Mahayana Treasure》(Fasc.2)says： One should recognise that those with Great Bodhicitta have Great Compassion as the first guidance.  We must firmly practise the Bodhisattva Path by entreating the Buddha Path above and rescuing sentient beings below.  We should follow in the spirit of all Buddhas and Bodhisattvas: to strive forward with courage and diligence, to do what others cannot do, to endure what others find difficult to endure.  One must possess the Four Immeasurable Hearts at each and every moment to rescue sentient beings.

The Buddha and Bodhisattvas embrace the Four Immeasurable Hearts (Benevolence, Compassion, Joy, Renunciation) to offer salvation to sentient beings.  For example: In the Buddha's past lives, at times of turmoil, He made offerings by sacrificing his eyes, arm, and even his life; with further examples of giving up his own body to feed tigers, and cutting his flesh to feed eagles.

Avalokitesvara Bodhisattva had long accomplished the Enlightenment limitless eons ago.  However, in order to rescue sentient beings, Avalokitesvara Bodhisattva returned to the boat of kindness to rescue sentient beings by searching their sounds of suffering and distress.  Samantabhadra Bodhisattva had traversed everywhere to fulfill the Ten Great Vows without any complaints nor regrets.  Ksitigarbha Bodhisattva made a vow to rescue every sentient beings from hells as proof of Bodhi.  They all fully reflect the four kinds of spirit possessed by Buddhas and Bodhisattvas in offering salvation to sentient beings: The Immeasurable Heart of Benevolence, the Immeasurable Heart of Compassion, the Immeasurable Heart of Joy and the Immeasurable Heart of Renunciation.

Modern people pledge to carry out voluntary work, make donations to charitable organisations, give blood and even donate organs to help and save people in danger; these behaviours are also the manifestation of Benevolence, Compassion, Joy and Renunciation.  One often hears ‘Don't stop being charitable just because it’s a small gesture’, and the saying ‘Taken from Society, Return to Society’.  Therefore, everyone has the ability, in various degrees, to develop the Four Immeasurable Hearts and to cultivate the Bodhisattva Path.  If everyone commits to virtuous practices, wouldn't the world be even more wonderful !