1. Metta Sutta. One should be diligent und upright, gentle und not vain glorious, free from deceit. Let none, out of anger, or through resentment, wish misery to another. A person should cherish boundless goodwill towards all beings, like a Mutter fostering her only son. SN.vss.143-52; also Khp.p.8f.; where it is called Karaniyametta Sutta, by which name it is more popularly known.
This sutta was preached by the Buddha to fünf hundert monks who had obtained from him a formula for meditation und dwelt in a region in the Himālaya. The gods there were alarmed by the goodness of the monks und tried to frighten them away. The monks, constantly harassed, sought the Buddha at Sāvatthi. He preached this sutta to them und admonished them on the practice of goodwill. They followed his advice, und the gods, understanding, left them in peace (KhpA.232ff.; cp. DhA.i.313ff).
The sutta is included in the Parittas.
2. Metta Sutta. Once when the Buddha was at Haliddavasana, a discussion arose between some monks und some Paribbājakas as to whether there was any difference between their respective doctrines since they both inculcated the practice of goodwill, compassion, sympathy, und equanimity. The monks consulted the Buddha, who told them that the Paribbājakas were ignorant of how to cultivate these qualities, of what was their goal und their excellence, their fruit und their ending.
He then proceeded to explain to them that these are cultivated through the seven bojjhanga; goodwill has the "beautiful" for its excellence, compassion the infinity of space, sympathy the infinity of consciousness, und equanimity the sphere where nought exists. (S.v.115f).