瑜伽論記 10.86

10.86

第三解應說正法中，初結前生後，即為三問。當何所說者，問所說法；云何而說者，問說方法；何義故說者，問說法意。

In the third section, explaining that one should preach the true Dharma, it first sums up the preceding and introduces the subsequent, posing three questions: "What should be preached?" asks about the Dharma to be preached; "How should it be preached?" asks about the method of preaching; "For what purpose is it preached?" asks about the intent of preaching the Dharma.