首楞嚴義疏注經 9.401

9.401

大聖深慈，勸不取滅，慇懃付囑，正為今時。若以今文望前發願，如一眾生未成佛，終不於此取泥洹。斯則師資相成，悲救一揆，四派入滅一何現權。

The Great Sage's profound compassion exhorts him not to take extinction, and his earnest entrustment is precisely for the present time. If we compare the present text with the earlier vows—'If even one sentient being has not attained Buddhahood, I will never take nirvāṇa here'—then teacher and pupil accomplish one another, unified in compassionate salvation; how expediential indeed was the four disciples' entering extinction!