法華義疏 2.234

2.234

息一切惡戒，後得累無不盡果，行一切善戒，後得法身德無不圓，度眾生戒亦令他得此二，故持於三戒自他俱證法身。

With the discipline of ceasing all evil, one later attains the fruit in which defilements are completely extinguished; with the discipline of practicing all good, one later attains the dharmakāya whose virtues are completely perfected; the discipline of saving sentient beings also causes others to attain these two. Therefore, by upholding the three disciplines, self and other both realize the dharmakāya.