大般涅槃經義記 4.340

4.340

Next, the second part broadly takes the aforementioned intermediate grade of sick people and divides them into five gates, contrasting them to reveal the Buddha. Why specifically bring up the intermediate grade to reveal the Buddha? Because the intermediate grade consists of Hīnayāna people, and the Hīnayāna is the direct counterpart to the Mahāyāna; by raising the small, the great is manifested, and the great meaning becomes clear, which is why they are specifically brought up. Therein, it first generally brings up the five people who have illness with respect to the Great [Vehicle]; it is not that the Tathāgata [has illness]. In terms of the Small [Vehicle], arhats and pratyekabuddhas have no illness, but now, when contrasted with the Great, they can also be said to have illness. From 'Which are...' onward, it specifically reveals the five people, contrasting them to reveal the Buddha, first questioning and then explaining.