So I have heard.
At one time the Buddha was staying in the sal forest of the Mallas at Upavattana near Kusinārā.
Now at that time several mendicants were staying not far from the Buddha in a wilderness hut. They were restless, insolent, fickle, scurrilous, loose-tongued, unmindful, lacking situational awareness and immersion, with straying minds and undisciplined faculties.
The Buddha saw those mendicants staying nearby.
Then, understanding this matter, on that occasion the Buddha expressed this heartfelt sentiment:
“Unguarded in body,
ruined by wrong view,
overcome with dullness and drowsiness,
you fall under Māra’s sway.
That’s why you should guard the mind,
with right thoughts your habitat,
and right view at the fore.
Having understood rise and fall,
a mendicant who has overcome dullness and drowsiness
would cast off all bad destinies.”