金光明最勝王經疏 2.425

2.425

贊曰：釋也。何故三身名無住處？以為二身故不住，以大悲故為物現身不住涅槃。亦應云不住生死，前明無餘已說不住生死。又以佛離漏餘謂涅槃，故今偏明不住涅槃，不謂住生死。所以亦言離於法身無有別佛者，以其法身從應化說性相合，云無別佛。彼二不住，故法身亦名不住。是故三身總名無住。又解：法身涅槃同體義別。若離法身有別體佛來住涅槃，可言住涅槃。既離法身無別佛，即同體故自不住自，故不住涅槃。前釋為勝，云離法身無別佛故，不云離涅槃無別佛故。

The commentary says: This is the explanation. Why are the three bodies called 'without an abiding place'? Because it is for the sake of the two bodies that he does not abide; out of great compassion he manifests bodies for beings and does not abide in nirvāṇa. One should also say that he does not abide in saṃsāra, but the preceding explanation of without remainder has already stated that he does not abide in saṃsāra. Furthermore, because a Buddha is free from defilements, others might call it nirvāṇa; therefore, it is now specifically explained that he does not abide in nirvāṇa, not that he abides in saṃsāra. As for the reason why it is also said, 'apart from the dharmakāya there is no other Buddha': because the dharmakāya, when spoken of from the perspective of the response and transformation [bodies], unites nature and characteristic, it says there is no other Buddha. Since those two do not abide, the dharmakāya is also called non-abiding. Therefore, the three bodies are collectively called non-abiding. Another explanation is: the dharmakāya and nirvāṇa have the same essence but different meanings. If, apart from the dharmakāya, there were a Buddha of distinct essence who came to abide in nirvāṇa, one could say he abides in nirvāṇa. Since apart from the dharmakāya there is no other Buddha, they are of the same essence, and thus self does not abide in self; therefore he does not abide in nirvāṇa. The former explanation is superior, because it says 'apart from the dharmakāya there is no other Buddha,' not 'apart from nirvāṇa there is no other Buddha.'