[444] Now at that time teachers (ācariya) did not conduct themselves properly toward their pupils (antevāsika). Those bhikkhus who were of few wishes … were annoyed, criticized, and complained: "How can teachers not conduct themselves properly toward their pupils?" Then those bhikkhus reported this matter to the Blessed One.
Then the Blessed One, on that ground and on that occasion, having had the Saṅgha of bhikkhus assembled, questioned the bhikkhus: "Is it true, bhikkhus, as is said, that teachers do not conduct themselves properly toward their pupils?"
"It is true, Blessed One."
… Having rebuked them and given a Dhamma talk, he addressed the bhikkhus: "Well then, bhikkhus, I shall lay down for teachers a duty (vatta) toward pupils, according to which teachers should conduct themselves properly toward their pupils."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.