I have heard that on one occasion the Blessed One was staying at
Kosambi, in Ghosita's Park. Now at that time Ven. Udayin was
sitting surrounded by a large assembly of householders, teaching
the Dhamma. Ven. Ananda saw Ven. Udayin 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. Udayin, lord, is sitting surrounded by a
large assembly of householders, teaching the Dhamma."
"It's not easy to teach the Dhamma to others, Ananda. The Dhamma
should be taught to others only when five qualities are established
within the person teaching. Which five?
"[1] The Dhamma should be taught with the thought, 'I will speak
step-by-step.'
"[2] The Dhamma should be taught with the thought, 'I will speak
explaining the sequence [of cause & effect].'
"[3] The Dhamma should be taught with the thought, 'I will speak
out of compassion.'
"[4] The Dhamma should be taught with the thought, 'I will speak
not for the purpose of material reward.'
"[5] 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, Ananda. The Dhamma
should be taught to others only when these five qualities are
established within the person teaching."
"Udayi Sutta: About Udayin" (AN 5.159), translated from the Pali
by Thanissaro Bhikkhu. Access to Insight, 3 July 2010,
http://www.accesstoinsight.org/tipitaka/an/an05/an05.159.than.html
. Retrieved on 11 June 2012.