注維摩詰經 5.188

5.188

肇曰：極上窮下齊以一觀，乃應平等也。生曰：涅槃雖非無，是表無之法也，故於外法中指舉此一事以對我明等也。

[Seng]zhao says: Only when reaching to the utmost above and plumbing to the lowest below, equalizing them in a single contemplation, does one accord with equality. [Dao]sheng says: Although nirvāṇa is not non-existent, it is a dharma that expresses non-existence; therefore, among external dharmas he specifically points out this one matter to contrast with the self and clarify their equality.