From Buddhism's Sacred Scripture: The Sutra of the Lotus of the Wonderful Dharma, Chapter 2, Part 2 of 4

Shakyamuni Budda provided a method for other sentient beings to be freed from the cycle of death and rebirth. In chapter two of The Lotus Sutra, The Buddha once said to Shariputra, “A wonderful Dharma (true teaching) such as this is preached by the Buddhas, the Tathagatas, at certain times. But like the blooming of udumbara (a blue lotus that blooms once every 3000 years), such times come very seldom. Shariputra, you and the others must believe me. Be assiduous, practiced meditation and wisdom, and so forth.”