金剛經纂要刊定記 4.43

4.43

疏即無下。即大乘之無餘四種之中，無住處涅槃也。謂不住菩薩變易生死，不住二乘灰斷涅槃，即真無住處名為無餘。若小乘無餘，如有情滅減不別。今不同彼，故云不共二乘。

The commentary's 'Namely without...': this is, among the four kinds of Mahāyāna nirvāṇa without residue, non-abiding nirvāṇa. That is to say, not abiding in a bodhisattva's transformational saṃsāra and not abiding in the two vehicles' ash-and-extinction nirvāṇa is the true non-abiding, termed 'without residue'. As for the Hīnayāna's without-residue, it is no different from sentient beings' annihilation. The present text is not like that, which is why it says 'not shared with the two vehicles'.