大毘盧遮那成佛經疏 2.14

2.14

The sūtra says: "Inner knower, outer knower." These are also alternative names for the knower. They are divided into two views: some hold the inner knower to be the self, saying that within the body there is another inner realiser that is the true self; others take the outer knower to be the self, saying that that which can know the realms of outer dust objects is the true self.