法華義疏 8.81

8.81

二義：一者、欲顯大涅槃即是種智，異二乘灰斷無為。二者、若言昔不說涅槃，於義不便，昔亦說三乘同入無餘故也。即以此文責光宅等師，若終歸於空既是灰斷涅槃，既言佛知涅槃，何得云昔不說灰斷涅槃耶？

There are two meanings: First, it wishes to reveal that the great nirvāṇa is identical to the knowledge of all modes, being distinct from the unconditioned state of ash-like extinction of the two vehicles. Second, if one were to say that he did not preach nirvāṇa in the past, it would be inappropriate to the sense, for in the past he also preached that the three vehicles equally enter the remainderless [nirvāṇa]. One may use this text to reprimand Master Guangzhai and others: if 'ultimately returning to emptiness' were the nirvāṇa of ash-like extinction, since it says the Buddha knows nirvāṇa, how could one say that in the past he did not preach the nirvāṇa of ash-like extinction?