[T]he Lotus Sūtra itself does not contain the words “buddha nature,” a concept developed in later Mahāyāna sūtras, such as the Nirvāṇa Sūtra. For that reason, some early Chinese exegetes argued that the Nirvāṇa Sūtra, and not the Lotus, represented the Buddha’s highest teaching. In contrast, the “three great masters of the Sui dynasty” – Huiyuan, Zhiyi, and Jizang – drew on the Sadāparibhūta chapter to argue that the idea of innate buddha nature is fully present in the Lotus Sūtra, even though that specific phrase does not occur there.