This was said by the Blessed One, said by the Arahant, as I have heard:
“Bhikkhus, a bhikkhu who is |lacking continuous effort::without energy, without application [anātāpī]| and is |without concern::without regret, without remorse, without a sense of shame [anottāpī]| is incapable of |full awakening::perfect understanding, enlightenment [sambodha]|, incapable of |Nibbāna::complete cooling, letting go of everything, deathless, freedom from calamity, the non-disintegrating [nibbāna]|, incapable of attaining the unsurpassed safety from bondage. But, bhikkhus, a bhikkhu who is |endowed with continuous effort::ardent, zealous, with energy, with application [ātāpī]| and |endowed with a sense of shame::with regret, with remorse, with concern [ottāpī]| is capable of full awakening, capable of Nibbāna, capable of attaining the unsurpassed safety from bondage.
The Blessed One spoke on this matter. In this regard, it is said:
”Lacking continuous effort and without concern,
a |lazy::procrastinating, inactive person, indolent [kusīta]| person who is |weak in effort::low in energy, lacking in endurance, lacking determination [hīnavīriya]|;
Overcome by dullness and drowsiness,
without shame, and without respect;
Such a bhikkhu is incapable,
of reaching the highest awakening.
But one who is mindful, discerning and meditates,
with continuous effort, with concern, and |diligent::doing one’s work or duty well, with alertness, carefulness and care [appamatta]|;
Having cut off the |fetter::chain, bond, thing which binds [saṁyojana]| of |birth and old age::being born and ageing [jātijarā]|,
such a one, in the here and now, reaches the highest awakening.”
This matter too was spoken by the Blessed One, as I have heard.