大般涅槃經疏 1.37

1.37

次、「臨涅槃時」下，聲時臨機道機時熟，不待不過臨赴之時。下文云「香山諸仙、拘尸力士、純陀、須跋善根成熟」，故唱涅槃，令其得入祕密之藏。《法華》云「應以滅度而得度者，示現滅度而度脫之。」即此義也。

Next, from 'when approaching nirvāṇa' onward, the time of the voice accords with the capacity: the capacity for the Path has matured at this time, brooking no delay and no passing beyond the time of approaching and attending. A lower passage says: 'The roots of goodness of the sages of the Fragrant Mountain, the wrestlers of Kuśinagara, Cunda, and Subhadra have matured', therefore he proclaimed nirvāṇa, enabling them to enter the secret treasury. The Lotus Sūtra says: 'To those who should be saved through extinction, he manifests extinction and saves them.' This is precisely the meaning.