大般涅槃經集解 55.66

55.66

案僧亮曰：上說持戒至涅槃因果相乘生因了因，未辨涅槃從何因有，故發問也。僧宗曰：難意欲令戒則無因故常，涅槃有因故無常也。寶亮曰：戒前既無因，應是常；涅槃以解脫為因，便應無常。

Sengliang comments: The above expounded the generative cause and the revealing cause succeeding one another from upholding precepts to nirvāṇa, but had not yet discerned from what cause nirvāṇa exists; hence he raises the question. Sengzong says: The intention of the challenge is to make precepts, being without a cause, permanent, and nirvāṇa, having a cause, impermanent. Baoliang says: Since precepts beforehand have no cause, they should be permanent; while nirvāṇa has liberation as its cause, so it should be impermanent.