Samyukta Āgama (2) 20
Bhikkhu Saṃyutta The Buddha sees a distracted monk 2
The simile of the flies
Thus have I heard, once, the Buddha was staying at the Deer Park near Vārāṇasī, where in former times the sages dwelt.
At that time the World-honored One put on his robe, took his begging bowl and entered Vārāṇasī to beg for food. At a deva shrine he saw a monk, his thoughts filled with evil, his mind desiring sensuality. Then the Buddha, the World-honored One said to the monk: “Monk, monk! You are planting the seeds of suffering, extremely vulgar and defiled, your senses stained with evil. Where there are juice stains, flies are bound to gather.” At that time the monk heard what the Buddha said and understood that the Buddha, the World-honored One, had read his thoughts. Fear arose in him and he hurried away, his hairs standing on end.
After the Buddha had finished his alms-round, eaten his meal, and washed his feet, he returned to the monks” quarters, where he entered his dwelling to meditate. When he came out again he took his seat in front of the assembled monks. The Buddha addressed them: “Today, when I went into the town on my alms-round, I saw a monk next to a deva shrine, his thoughts filled with evil, his mind desiring sensuality. So I said: “Monk, monk! You are planting seeds of suffering, extremely vulgar and defiled, your senses stained with evil. Where there are juice stains, flies are bound to gather.” When the monk heard what I said, fear arose in him and he hurried away, his hairs standing on end.” When the Buddha had finished saying this, one monk rose from his seat, and holding his hands with palms together in salutation said to the Buddha: “World-honored One! What is called ‘the seeds of suffering,’ what is ‘vulgar and defiled,’ what is ‘stained with evil,’ what is meant with ‘flies gathering?’” The Buddha answered: “Listen carefully, listen carefully! I will explain this: Anger and hatred is called ‘to plant seeds of suffering,’ the mind indulging in the five sensual pleasures is called ‘vulgar and defiled.’ When the six senses are not controlled in moral practice, this is called ‘stained with evil.’ That which causes the persistence of affliction and the arising of ignorance, arrogance, brazenness and shamelessness; that which causes the arising of the fetters is called ‘flies gathering.’”
Then the Buddha spoke this verse:
“When one does not control the senses / one strengthens desire and attachment, and plants seeds of suffering, vulgar and defiled actions produce a constant stream / of related desirous, malevolent, and violent thoughts.
If in a village or in an empty uninhabited place / one always keeps one’s heart free from transient pleasures, and with one’s very body practices right meditation / cultivates supernormal powers, and attains the three knowledges, then one attains happiness, sleeps peacefully / and can vanquish the thought-flies completely.
Through practice one becomes firmly established / is able to follow the noble way to the good realm(s). Having attained the way of right knowledge, one will never turn back / but enter into Nirvāṇa and the bliss of silent extinction.”
When the Buddha had finished speaking, the monks, having listened to what he had said, were happy and remembered it well.