About Udāyin (On Teaching the Dhamma)
Udāyin Sutta  (AN 5:159)

I have heard that on one occasion the Blessed One was staying near Kosambī at Ghosita’s monastery. Now at that time Ven. Udāyin was sitting surrounded by a large assembly of householders, teaching the Dhamma. Ven. Ānanda saw Ven. Udāyin sitting surrounded by a large assembly of householders, teaching the Dhamma, and on seeing him went to the Blessed One. On arrival, he bowed down to the Blessed One and sat to one side. As he was sitting there he said to the Blessed One: “Ven. Udāyin, lord, is sitting surrounded by a large assembly of householders, teaching the Dhamma.”

“It’s not easy to teach the Dhamma to others, Ānanda. The Dhamma should be taught to others only when five qualities are established within the person teaching. Which five?

“The Dhamma should be taught with the thought, ‘I will speak step-by-step.’

“The Dhamma should be taught with the thought, ‘I will speak explaining the sequence (of cause & effect).’

“The Dhamma should be taught with the thought, ‘I will speak out of compassion.’

“The Dhamma should be taught with the thought, ‘I will speak not for the purpose of material reward.’

“The Dhamma should be taught with the thought, ‘I will speak without hurting myself or others.’1

“It’s not easy to teach the Dhamma to others, Ānanda. The Dhamma should be taught to others only when these five qualities are established within the person teaching.”

Note

1. According to the Commentary, hurting oneself and others means exalting oneself and disparaging others.

See also: AN 2:92; AN 5:202; AN 6:86—88