勸發菩提心集 3.133

3.133

難行慧者，有三種：能知甚深法無我智，名第一難；能了有情調伏方便智，名第二難；了知一切所知境界無障礙智；名第三難。

Prajñā difficult to practice has three kinds: the wisdom capable of knowing the profound selflessness of phenomena is called the first difficulty; the wisdom capable of understanding the skillful means for taming sentient beings is called the second difficulty; and the unimpeded wisdom that understands the realms of all that is to be known is called the third difficulty.