[W]hen Śākyamuni Buddha who is a compassionate father, the Buddha of Many Treasures who is a compassionate mother, as well as Buddhas from all the worlds throughout the universe who assist the compassionate parental Buddhas to bear witness to the truth of the Lotus Sūtra came together in one place shining brightly as if the suns and moons were put together, the Buddha addressed the great crowd: “Who will uphold and recite and spread this Lotus Sūtra after My passing? State your vow now before Me.” The Buddha repeated this three times (“Appearance of a Stupa of Treasures” chapter). Then numerous great bodhisattvas filling the worlds in eight directions numbering 400 tens of thousand millions nayuta all vowed, lowered their heads deeply, held hands in the form of gasshō, and said in unison: “We will do exactly as the World Honored One commanded us.” They swore this three times loudly without sparing their voices (“Transmission” chapter). How can they not bear the suffering of the practicers of the Lotus Sūtra?

Fan Yü-ch’i of ancient China gave his head to Ching K’o, and a man called Chi Cha presented his treasured sword upon the gravestone of the Lord of Hsü in order to fulfill their promises. They were foreigners in China, uncivilized as Ainus. Nevertheless, they kept their promises at the cost of their lives, how much more so the great bodhisattvas who from the first have been deeply compassionate and vowed to bear the suffering of other people! Even without the commandment of the Buddha, how can they abandon the practicer of the Lotus Sūtra? Moreover, the Lotus Sūtra is the one that enabled them to attain Buddhahood, and receiving the solemn words of the Buddha, they made a vow respectfully before the Buddha. There is no question whatsoever that they will help the practicers of the Lotus Sūtra.

Kitō Shō, Treatise on Prayers, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 65-66