金光明最勝王經疏 2.383

2.383

贊曰：釋所以也。由此三身於自他利各得自在，俱成種種無邊用故。故《成唯識》云「如是三身雖皆具足無邊功德，而各有異。」言而得自在，自在有三，如《雜集》第十二云「依止自在修亦有三種：一身自在，即自性身及受用身。二行自在，即變化身。三說自在，謂能說六度等。既緣此、求此、依此而求此，故知佛身有三自在，成就無邊二利用故。」

Commentary: This explains the reason. Because these three bodies each attain mastery regarding benefit for oneself and others, and both accomplish various boundless functions. Therefore the Cheng weishi lun says: "Although these three bodies are all complete with boundless merits, they each have differences." As for 'attain mastery', mastery has three kinds. As the twelfth fascicle of the Abhidharmasamuccayavyākhyā states: "Cultivation of reliance on mastery also has three kinds: first, mastery of the body, namely the svabhāvakāya and the saṃbhogakāya; second, mastery of conduct, namely the nirmāṇakāya; third, mastery of exposition, which means being able to expound the six pāramitās and so forth. Since one takes this as an object, seeks this, and relies upon this to seek this, one therefore knows that the Buddha bodies have three masteries, accomplishing the boundless functions of the two benefits."