[20] Now at that time the group-of-six bhikkhus chanted the Dhamma with a drawn-out song-like intonation. People complained, criticized, and spread it about, saying: "Just as we ourselves sing, even so do these ascetics, sons of the Sakyan, chant the Dhamma with a drawn-out song-like intonation." Bhikkhus heard those people complaining, criticizing, and spreading it about. Those bhikkhus who were of few wishes … they complained, criticized, and spread it about: "How indeed can the group-of-six bhikkhus chant the Dhamma with a drawn-out song-like intonation?" Then those bhikkhus reported this matter to the Blessed One. … "Is it true, as they say, bhikkhus …" … "It is true, Blessed One." … Having given a talk on the Dhamma, he addressed the bhikkhus: "Bhikkhus, there are these five dangers (ādīnava) for one who chants the Dhamma with a drawn-out song-like intonation: he himself becomes attached to that sound; others too become attached to that sound; householders complain; for one intent on the modulation of the voice there comes a break in his concentration (samādhi); and the later generation falls into following his example. These, bhikkhus, are the five dangers for one who chants the Dhamma with a drawn-out song-like intonation. Bhikkhus, the Dhamma should not be chanted with a drawn-out song-like intonation. Whoever should so chant it commits an offense (āpatti) of wrong-doing (dukkaṭa)."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.