This was said by the Blessed One, said by the Arahant, as I have heard:

"Bhikkhus, a bhikkhu should dwell wakeful, mindful, fully aware, collected, joyful, tranquil, and there, he should discern with clarity at a suitable occasion in regard to the wholesome mental qualities. 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 [of full awakening] here and now, or, if there is any residual clinging for existence, the state of non-returning."

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, they dispel the darkness.

Therefore, cultivate wakefulness, The bhikkhu who is with continuous effort, discerning, and who gains jhānas at will; Having cut off the fetter of being born and ageing, will realize the highest awakening right here."

This matter too was spoken by the Blessed One, as I have heard.