[568] On one occasion the Blessed One was dwelling at Bārāṇasī, in the Deer Park at Isipatana. Then, in the morning, the Blessed One dressed, took his bowl and robe, and entered Bārāṇasī for alms. While walking for alms near the fig tree at the cattle-yoke (goyogamilakkha), the Blessed One saw a certain bhikkhu — empty of inner delight, taking delight in externals, muddled in mindfulness, without clear comprehension, unconcentrated, with a wandering mind (citta), his sense faculties loose — and having seen him, he said to that bhikkhu: "Bhikkhu, do not make yourself putrid (kaṭuviya). That flies will not pursue and attack one who has made himself putrid, soaked with the stench of carrion (āmagandha) — this is impossible." Then that bhikkhu, admonished by the Blessed One with this exhortation, was moved to a sense of urgency (saṃvega).
Then the Blessed One, having walked for alms in Bārāṇasī, after the meal, when he had returned from the alms round, addressed the bhikkhus: "Bhikkhus, here this morning I dressed, took my bowl and robe, and entered Bārāṇasī for alms. While walking for alms near the fig tree at the cattle-yoke, I saw, bhikkhus, a certain bhikkhu — empty of inner delight, taking delight in externals, muddled in mindfulness, without clear comprehension, unconcentrated, with a wandering mind, his sense faculties loose — and having seen him, I said to that bhikkhu: 'Bhikkhu, do not make yourself putrid. That flies will not pursue and attack one who has made himself putrid, soaked with the stench of carrion — this is impossible.' Then, bhikkhus, that bhikkhu, admonished by me with this exhortation, was moved to a sense of urgency."
When this was said, a certain bhikkhu said to the Blessed One: "What, venerable sir, is 'the putrid'? What is 'the stench of carrion'? What are 'the flies'?"
"Covetousness (abhijjhā), bhikkhu, is 'the putrid'; ill will (byāpāda) is 'the stench of carrion'; evil, unwholesome thoughts are 'the flies'. That flies will not pursue and attack one who has made himself putrid, soaked with the stench of carrion — this is impossible.
Upon one unguarded in eye and ear,
unrestrained in the sense faculties,
the flies will pursue —
intentions based on lust.
A bhikkhu who has made himself putrid,
soaked with the stench of carrion,
is far from Nibbāna,
a partaker only of vexation.
Whether in village or in wilderness,
not having gained the peace of his own self,
the fool of poor wisdom wanders on,
beset by flies.
But those who are accomplished in virtue,
who delight in wisdom and in peace,
those at peace sleep happily,
having destroyed the flies."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.