大般涅槃經義記 8.156

8.156

合中，「佛性」合前寶藏眾生不見，「有知識」下合前知識而語等也。

In the application, "buddha-nature" applies to the earlier treasure trove that sentient beings do not see; from "there is a spiritual friend" onward applies to the earlier spiritual friend speaking, and so forth.