法苑珠林 30.40

30.40

As stated in the Śāriputraparipṛcchā-sūtra: Śāriputra said to the Buddha, "Why did the Tathāgata inform Śakra, Devendra, and the Four Heavenly Kings, saying: 'Before long I shall enter parinirvāṇa. You shall each protect and maintain my Dharma in your respective regions. After I pass away, the four great monks—Mahākāśyapa, Piṇḍola, Kuntadhāna, and Rāhula—shall abide without entering nirvāṇa to circulate my Dharma'?" The Buddha said, "It is merely that during the semblance teaching the root of faith is slight and frail; although they generate faith, they cannot be steadfast. Although [they may try] to evoke the Buddhas' disciples through single-minded devotion for consecutive years, it is not equal to a single moment of wholesome thought while the Buddha was in the world. Therefore, when Maitreya descends to be born, I permit you to enter nirvāṇa."