[251] Bhikkhus, I have come to know (upaññāsiṃ) two things: non-contentment with regard to wholesome states, and unrelenting exertion in striving (padhāna). Indeed, bhikkhus, I strove unrelentingly, thinking: "Willingly, let only skin, sinews, and bones remain; let the flesh and blood in this body dry up — so long as what is to be attained by manly strength, by manly energy (vīriya), by manly exertion has not been attained, there shall be no slackening of energy." By me, bhikkhus, awakening (bodhi) was attained through heedfulness; the unsurpassed security from bondage (yogakkhema) was attained through heedfulness. If you too, bhikkhus, would strive unrelentingly, thinking: "Willingly, let only skin, sinews, and bones remain; let the flesh and blood in this body dry up — so long as what is to be attained by manly strength, by manly energy, by manly exertion has not been attained, there shall be no slackening of energy," then you too, bhikkhus, before long, will dwell having realized for yourselves with direct knowledge (abhiññā), in this very life, and having entered upon, that unsurpassed culmination of the holy life (brahmacariya) for the sake of which clansmen rightly go forth from the home life into homelessness. Therefore, bhikkhus, you should train thus: "We shall strive unrelentingly, thinking: 'Willingly, let only skin, sinews, and bones remain; let the flesh and blood in this body dry up — so long as what is to be attained by manly strength, by manly energy, by manly exertion has not been attained, there shall be no slackening of energy.'" Thus indeed, bhikkhus, should you train.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.