On one occasion Ven. Maha Kaccana was staying at Madhura in the Gunda Forest. Then Kandarayana the brahman went to Ven. Maha Kaccana and on arrival exchanged courteous greetings with him. After an exchange of friendly greetings & courtesies, he sat to one side. As he was sitting there, he said to Ven. Maha Kaccana, "I have heard it said, Master Kaccana, that, 'Kaccana the contemplative does not raise his hands in respect to aged, venerable brahmans — advanced in years, come to the last stage of life — nor does he rise up to greet them, nor does he offer them a seat.' Insofar as you don't raise your hands in respect to aged, venerable brahmans — advanced in years, come to the last stage of life — nor rise up to greet them, nor offer them a seat, that is simply not right, Master Kaccana."
"Brahman, the Blessed One — the one who knows, the one who sees, worthy & rightly self-awakened — has declared the level of one who is venerable and the level of one who is a youngster. Even if one is venerable — 80, 90, 100 years old — yet if one partakes of sensuality, lives in the midst of sensuality, burns with sensual fever, is chewed up by sensual thoughts, and is eager in the search for sensuality, then one is reckoned simply as a young fool, not an elder.
"But if one is a youngster, youthful — a black-haired young person endowed with the blessings of youth in the first stage of life — yet does not partake of sensuality, does not live in the midst of sensuality, does not burn with sensual fever, is not chewed up by sensual thoughts, and is not eager in the search for sensuality, then one is reckoned as a wise elder."
When this was said, Kandarayana the brahman rose up from his seat, arranged his cloak over one shoulder, and bowed down at the feet of the monks who were youngsters, [saying,] "You, sirs, are the venerable ones, standing on the level of those who are venerable. We are the youngsters, standing on the level of those who are youngsters.
"Magnificent, Master Kaccana! Magnificent! Just as if he were to place upright what was overturned, to reveal what was hidden, to show the way to one who was lost, or to carry a lamp into the dark so that those with eyes could see forms, in the same way has Master Kaccana — through many lines of reasoning — made the Dhamma clear. I go to Master Gotama for refuge, to the Dhamma, & to the community of monks. May Master Kaccana remember me as a lay follower who has gone for refuge from this day forward, for life."
See also: AN 3.94