大般涅槃經義記 2.187

2.187

Next, using a simile, he questions the questioner in return. From "no" onward, the questioner answers correctly. From "self-correcting" onward, it reveals the teaching in accordance with it, clarifying that self-correcting and the others are all identical to nirvāṇa and therefore can be one. In clarifying the dharmakāya, it first clarifies that the substance of the Tathāgata's dharmakāya is permanent; from "as the Buddha said: 'I have long crossed the ocean of afflictions'" downward, it sweeps away doubts regarding the traces and establishes its meaning of permanence. In the former, first there is a dialogue discerning permanence; second, Kāśyapa grasps and understands; third, the Buddha confirms and approves.