金光明最勝王經疏 3.23

3.23

贊曰：明常也。眾生界無盡，故現命無盡，由此說常。此約緣常，有隨緣應說常。無性《攝論》云「佛受用身及變化身既是無常，云何經說如來身常？」此問此二所依法身常故。又於等流身及變化身，以恒受用，無休廢故、不永絕故。無性釋云「謂此二身雖是無常，然依法身常，法身常故亦說為常。言身常者，或體是常；或依常身故名身常，是異門常非自性常。」乃至云「猶如世間言常受樂，雖非受樂常無間斷，而得說言此常受樂。佛受用身當知亦爾。」準《大莊嚴論》第三云「一切諸佛悉同常住。由自性常故，一切諸佛自性身常住。由無間常故，一切諸佛食身常住。由相續常故，一切諸佛化身常住。」此中食身攝自他受用說，為自利即自受；為他說法名為食身，即他受用。而《攝論》等同。

Commentary: Explaining permanence. Because the realm of sentient beings is unending, its manifested lifespan is unending; hence it is spoken of as permanent. This refers to permanence through conditions: there is permanence spoken of as conforming to conditions. Asabhāva's Commentary on the Mahāyānasaṃgraha says: 'Since the Buddha's saṃbhogakāya and nirmāṇakāya are impermanent, why do the sūtras say that the Tathāgata's body is permanent?' This asks about their permanence because the dharmakāya on which these two rely is permanent. Furthermore, with respect to the niṣyandakāya and nirmāṇakāya, because of constant enjoyment, without cessation or final severance, Asabhāva explains: 'Although these two bodies are impermanent, yet they rely on the permanence of the dharmakāya, and because the dharmakāya is permanent they are also spoken of as permanent. When speaking of the permanence of the body, either its essence is permanent, or it is called permanent because of relying on a permanent body; this is permanence by alternative designation, not permanence by intrinsic nature.' It goes on to say: 'Just as in the world people speak of