The Buddha also declares in the Lotus Sūtra: “For anyone who keeps this sūtra in this evil world during the Latter Age of Degeneration” in the “Variety of Merits” chapter; “Buddhas joyfully display their immeasurable, supernatural powers in praise of those who will keep this sūtra after My extinction” in the “Divine Powers of the Buddha” chapter; “Propagate this chapter throughout this Sahā World in the latter five-hundred year period after My extinction lest it should be lost” in the “Previous Life of Medicine King Bodhisattva” chapter and “This sūtra is a panacea for sick people in this Sahā World” in the same chapter. The Buddha also states in the Nirvana Sūtra: “Suppose there are seven children, their parents love them all equally but care most for a sick child.” Icchantika and slanderers of the True Dharma are like the first and second children of the seven whom parents care most about. Of many illnesses, slandering the Lotus Sūtra is the most serious. Of many medicines, “Namu Myōhō Renge Kyō” is the most wonderful medicine.

Hokke Shuyō Shō, Treatise on the Essence of the Lotus Sūtra, Writings of Nichiren Shōnin, Doctrine 2, Page 212-213