大般涅槃經集解 68.26

68.26

案寶亮曰：解第七人。從羅漢以上至於諸佛，通名為一人，故借喻於神龜能水陸俱行。但水陸兩事，如文所合。世間河中雖有七種之別，同不離於水。涅槃中亦爾，乃有七人之異，亦通不離佛性之水。但佛性之義隨事而收，或緣因、或境界，如是眾多若因若果，盡是佛性。

Baoliang states: Explaining the seventh person. From the arhat on up to the Buddhas, they are comprehensively designated as one person; hence the metaphor is borrowed from the divine turtle that can travel on both water and land. However, the two matters of water and land correspond to what is in the text. Although there are seven kinds of distinctions in the worldly river, none of them departs from the water. In nirvāṇa it is likewise: though there are the differences of the seven persons, none of them departs from the water of buddhadhātu. Yet the meaning of buddhadhātu is subsumed according to circumstances, whether as conditioning cause or as cognitive object; such numerous factors, whether causes or fruits, are all buddhadhātu.