瑜伽論記 6.20

6.20

又正說法，略有二種。所謂隨順、及無染污。廣說二十如菩薩地當說者，此正說法隨順二空所顯真如，及無希望而為他說，故無染污。

Regarding "moreover, proper exposition of the Dharma is briefly of two kinds, namely, conforming [to truth] and being undefiled; when explained extensively there are twenty, as will be explained in the Bodhisattvabhūmi": this proper exposition of the Dharma conforms to the tathatā revealed by the two kinds of emptiness, and it is expounded for others without expectation [of reward], and is therefore undefiled.