[What Śākyamuni] preached during His life of fifty years is Mahāyāna (greater vehicle) as a teaching of salvation when compared to geten and gedō. Ever since His attainment of Buddhahood till the eve of His entering Nirvana, He preached only the truth.

Considering the 80,000 teachings preached by the Buddha in various sūtras for fifty years, however, we see differences among them, such as those between Hinayāna and Mahāyāna Buddhism, provisional and ultimate sūtras, exoteric and esoteric teachings, gentle and rough expressions, genuine and expedient words or true and false opinions. The Lotus Sūtra alone among them represents the true words of our Lord Śākyamuni Buddha and various Buddhas residing in the world throughout the universe in the past, present, and future.

Kaimoku-shō, Open Your Eyes to the Lotus Teaching, Writings of Nichiren Shōnin, Doctrine 2, Page 34