It is preached in the Lotus Sūtra, in the second fascicle (“A Parable” chapter): “Suppose there is a person who does not believe in this sūtra and instead disparages it or despises, hates, or bears a grudge against those who uphold this sūtra by reading, reciting, or copying it. Such a person will fall into the Hell of Incessant Suffering upon death and will continue to wander about the hell for innumerable kalpa (aeons).” The seventh fascicle (“Never-Despising Bodhisattva” chapter) of the same sūtra states: “(Such a person) will suffer in the Hell of Incessant Suffering for as long as 1,000 kalpa (aeons).” The third fascicle (“The Parable of a Magic City”) states “for 3,000 dust-particle kalpa. ” And the sixth fascicle (“The Life Span of the Buddha”) says “for 500 (million) dust-particle kalpa. ” The Nirvana Sūtra declares: “In case one is crushed to death by a wild elephant, one will not fall into the three evil realms. However, when one is killed by an evil friend, one will inevitably fall into them. ”

Toki-dono Gosho, A Letter to Lord Toki, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 115-116