法華玄義釋籤 19.21

19.21

次以三佛性難，中三：初更牒《涅槃》、《般若》所明實相法性為正因，對餘二性為三因。次重引《金剛論》，證般若為了因佛性。三「但名異」下舉譬結難。

Next, within refuting with the three Buddha-natures, there are three [parts]: first, he further cites the true mark and dharma-nature clarified in the Nirvāṇa [Sūtra] and Prajñā as the direct cause, contrasting them with the other two natures as the three causes. Second, he re-cites the Vajracchedikā-śāstra to prove that Prajñā is the revealing-cause Buddha-nature. Third, from "It is only that the names differ..." downward, he provides an analogy to conclude the refutation.