The Four Immeasurables
Loving-kindness, compassion, sympathetic joy, and equanimity.
The Four Immeasurables (Brahmaviharas) are boundless states of mind: metta (loving-kindness), karuna (compassion), mudita (sympathetic joy), and upekkha (equanimity). Cultivating these creates a vast, open heart.
May all beings be happy. May all beings be free from suffering.
The Four Immeasurables are called 'immeasurable' because their objects are infinite.
Metta Sutta