The Tipiṭaka in Three Languages

Satipaṭṭhānavibhaṅgasuttantabhājanīya

Abhidhammapiṭaka · Vibhaṅga · Vol. 35 · Section 437

[437] "Ardent" (ātāpī): Herein, what is ardor (ātappa)? That which is the mental arousing of energy (cetasiko vīriyārambho) … right effort (sammāvāyāma) — this is called ardor. He is endowed with, fully endowed with, has reached, fully reached, has attained, fully attained, and is possessed of this ardor. Therefore he is called "ardent."

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 5 other places