Filial devotion preached in Confucianism is limited to this life. Confucian sages and wise men exist in name only because they do not help parents in their future lives. Non-Buddhist religions in India know of the past as well as the future, but they do not know how to help parents. Only Buddhism is worthy of being the way of sages and wise men, as it helps parents in future lives. However, both the Mahāyāna and Hinayāna sūtras expounded before the Lotus Sūtra preach Buddhahood in name only, without substance. Therefore the practicers of such sūtras will not be able to obtain Buddhahood even for themselves, not to speak of helping parents obtain Buddhahood. Now coming to the Lotus Sūtra, when the enlightenment of women was revealed, the enlightenment of mothers was realized; and when a man as wicked as Devadatta could attain Buddhahood, the enlightenment of fathers was realized. These are the two proclamations of the Buddha in the “Devadatta” chapter, and this is the reason why the Lotus Sūtra is the sūtra of the filial way among all the Buddhist scriptures.

Kaimoku-shō, Open Your Eyes to the Lotus Teaching, Writings of Nichiren Shōnin, Doctrine 2, Page 91