摩訶止觀 4.192

4.192

復次，欲者，如薩陀波崙欲聞般若，不自惜身命。精進者，為聞般若故，七日七夜閑林悲泣；七歲行立不坐不臥。念者，常念我何時當聞般若，更無餘念。巧慧者，雖有留難，留難不能難。如賣身，魔不能蔽；隱水，更能刺血。轉魔事為佛事，即巧慧。一心者，決志不移，不復二念也。

Furthermore, desire is like Sadāprarudita desiring to hear prajñā, not sparing his own body or life. Vigor means that for the sake of hearing prajñā, he wept in grief in a solitary forest for seven days and seven nights, and walked and stood for seven years without sitting or lying down. Mindfulness means constantly thinking, 'When shall I hear prajñā?' with no other thoughts. Skillful wisdom means that although there were obstacles and difficulties, the difficulties could not hinder him; as when selling his body, Māra could not obstruct him, and when [Māra] hid the water, he could still pierce himself for blood. Turning Māra's deeds into Buddha's deeds is skillful wisdom. Single-mindedness means his resolute determination did not waver, and he had no second thought.