From Buddhism's Sacred Scripture: The Sutra of the Lotus of the Wonderful Dharma, Chapter 3, Part 2 of 8

At that time the Buddha said to Sariputra, “Now, in the midst of this great assembly of heavenly and human beings, shramanas (wandering monks), Brahmans (members of a higher social class) and so forth, I say this. In the past, under twenty thousand million Buddhas, for the sake of the unsurpassed way I have constantly taught and converted you. And you throughout the long night followed me and accepted my instruction. Now, because I want to make you recall to mind the way that you originally vowed to follow, for the sake of the voice-hearers I am preaching this Great Vehicle sutra called the Lotus of the Wonderful Dharma, a Dharma to instruct the Bodhisattvas, one that is guarded by the Buddhas.