This was said by the Blessed One, said by the Arahant, as I have heard:
“Bhikkhus, a bhikkhu should dwell |wakeful::lucid, awake, alert [jāgara]|, |mindful::mindfulness of body in and of itself, of felt experience in and of itself, of mind in and of itself, of mental qualities in and of itself [sati]|, |fully aware::with attentiveness, with clear and full comprehension [sampajañña]|, |collected::composed, settled [samāhita]|, joyful, |tranquil::serene, calm [vippasanna]|, and there, he should |discern::see distinctly, observe [vipassi]| with clarity at a suitable occasion in regard to the |wholesome::healthy, beneficial, useful [kusala]| |mental qualities::inherent qualities, reality [dhamma]|. Bhikkhus, for a bhikkhu who dwells wakeful, mindful, fully aware, collected, joyful, tranquil, and there, discerning with clarity at a suitable occasion in regard to the wholesome mental qualities, one of two results is to be expected: either |final knowledge::spiritual insight [aññā]| [of full awakening] here and now, or, if there is any |residual clinging for existence::remnant of grasping for renewed becoming [upādisesa]|, the state of |non-returning::third stage of awakening where the five lower fetters of personal existence view, doubt, adherence to rules and observances, sensual desire, and ill-will are permanently dropped [anāgāmitā]|.”
The Blessed One spoke on this matter. In this regard, it is said:
“Those who are wakeful, listen to this,
You who are asleep, wake up;
Being awake is better than being asleep,
For the wakeful, there is no fear.
One who is wakeful, mindful, and fully aware,
collected, joyful, and tranquil;
By thoroughly examining the mental qualities at the proper time,
|unified::becoming whole, becoming integrated [ekodibhūta]|, they dispel the |darkness::ignorance, gloom, murkiness [tamas]|.
Therefore, cultivate wakefulness,
The bhikkhu who is |with continuous effort::ardent, zealous, with energy, with application [ātāpī]|, |discerning::astute, wise [nipaka]|, and |who gains jhānas at will::accomplished in meditation, who has deep states of meditation [jhānalābhī]|;
Having cut off the fetter of |being born and ageing::birth and old age [jātijarā]|,
will realize the highest awakening right here.”
This matter too was spoken by the Blessed One, as I have heard.