佛說觀佛三昧海經 8.27

8.27

The Buddha told Ānanda: “After the Buddha's parinirvāṇa, when the hosts of devas, nāgas, yakṣas, śramaṇas, and brāhmaṇas ask: ‘What retribution did the Buddha, the Bhagavat, attain by cultivating pure conduct in past lives, being pure and devoid of desire?’ you should answer them: ‘The Buddha possesses the horse-king sheath mark, which is proportionate with his body, perfectly filled in its seven convexities, pure inside and out like a vajra vessel. For the sake of saving sentient beings, he manifests this mark, along with immeasurable transformation Buddhas, light, and wondrous lotus clouds. Such a body arises from countless lives of being unstained and at peace, properly upholding moral discipline, wisdom, and the śīla-pāramitā.’”