大般涅槃經義記 6.213

6.213

自下第二辯明此經常存不滅，令人敬學。於中，初就迦葉佛時辯明此經常在不滅，「若有眾生我見無我」下就餘佛時辯明此經常存不滅。何故先就迦葉佛時說不滅乎？迦葉佛法住世七日即便滅盡，似無此經，故先就之明有不滅。迦葉先問，問由何生？因前而起，如來上言《大涅槃經》有行不滅，迦葉佛時眾生有行，何故彼法七日便滅？故為斯問。

From here below is the second [section], which explains that this sūtra constantly abides and is never destroyed, causing people to revere and study it. Within this, first, with reference to the time of Kāśyapa Buddha, it explains that this sūtra is constantly present and not destroyed; from "If there are sentient beings who [hold] the view of self or non-self" below, with reference to the times of other buddhas, it explains that this sūtra constantly abides and is not destroyed. Why does it first speak of non-destruction with reference to the time of Kāśyapa Buddha? The Dharma of Kāśyapa Buddha abode in the world for only seven days and then was completely extinguished, as if this sūtra did not exist; therefore, with reference to him first, it clarifies that it exists and is not destroyed. Kāśyapa first asks: from where does his question arise? It arises because of what came before: above, the Tathāgata said that when there is practice, the Mahāparinirvāṇa Sūtra is not destroyed; at the time of Kāśyapa Buddha, sentient beings possessed practice, so why was that Dharma extinguished in only seven days? It is for this reason that he raises this question.