大乘入道次第開決 1.126

1.126

但化彼行何假身同等者。此問意者。菩薩所化通乎三乘。但可說法化二乘人。豈要同行二乘行也。不爾便是和光同塵。便與涅槃經文違背。答之意云。菩薩為化他令行故。縱二乘行亦須示行。自嫌不行人不學故。故法花云。內祕菩薩行外現是聲聞。雖少欲知足而實淨佛道。涅槃但和其光而不同塵。此義故不乖於理也。

Regarding "simply converting their conduct, why borrow the same bodily form, etc.": the intention of this question is: the converts of a bodhisattva extend across the three vehicles; they need only teach the Dharma to convert people of the two vehicles, so why must they practice the conduct of the two vehicles together with them? If not so, then this would be harmonizing one's light and mingling with the dust, which would contradict the text of the Nirvāṇa-sūtra. The intention of the answer says: because a bodhisattva acts to convert others and cause them to practice, even with the conduct of the two vehicles they must also manifest its practice; for if they themselves dislike it and do not practice it, people will not learn it. Thus the Lotus Sūtra says: "Inwardly concealing bodhisattva conduct, outwardly manifesting as a śrāvaka; although having few desires and knowing contentment, in reality they purify the Buddha path." The Nirvāṇa[-sūtra] only means harmonizing their light without mingling with their dust; therefore, this meaning does not go against principle.