Visuddhimagga VIII-73

Tayo ca suttantāti adhicittaṃ, sītibhāvo, bojjhaṅgakosallanti ime tayo suttantā vīriyasamādhiyojanatthaṃ veditabbāti ayamettha adhippāyo.

（8）─（10）「以三经典」──即增上心，清凉，觉支善巧等三经，当知精进与定的结合，是这（三经）的意义。

Ñ(VIII,73): 8-10. As to the three suttantas: the intention here is this: it should be understood that the three suttantas, namely, those on higher consciousness, on coolness, and on skill in the enlightenment factors, have as their purpose the linking of energy with concentration.