Dividing the preachings of fifty years in His lifetime into two, provisional and true, Śākyamuni Buddha Himself clearly declared that we should discard provisional sūtras and seek refuge in the true sūtras. Thus, it is stated in the second chapter on “Expedients” of the Lotus Sūtra that the Buddha preached provisional sūtras in forty years or so because He was afraid that “the people would be unable to understand and sink in pain if He praised only the way to Buddhahood.” He, nevertheless, was also concerned that “if I guide people merely with Hinayāna dharma, even just one person, I would be committing the sin of greed.” Therefore, in order to avoid committing such a sin and upholding “His basic purpose of leading people into Mahāyāna teaching,” the Buddha expounded the Lotus Sūtra, achieving His purpose.

Shugo Kokka-ron, Treatise on Protecting the Nation, Writings of Nichiren Shōnin, Doctrine 1, Page 27