大般涅槃經義記 4.216

4.216

自下第六有難解者，迦葉對佛問答重顯。有何難解？向前雖說人有差別、無差別義，佛性差別、無差別義猶自未顯，故下辯之。於中有二：一問性無差，如來廣釋；第二「云何性差別」下問性差別，如來廣解。

From here below is the sixth [section], where what is difficult to understand is clarified again through questions and answers between Kāśyapa and the Buddha. What is difficult to understand? Although the meaning of persons having differences and having no differences was spoken of earlier, the meaning of buddha-nature having differences and having no differences was still not yet apparent, so it is elucidated below. In this there are two [parts]: first, asking about the nature having no differences, which the Tathāgata explains extensively; second, from "Why is there differentiation of natures?" below, asking about the nature having differences, which the Tathāgata explains extensively.