Personalities of the Buddhist Suttas
One of three brothers ... He lived on the banks of the Neranjara with five hundred disciples. Further down the river lived his brothers Nadi-Kassapa with three hundred disciples and Gaya-Kassapa with two hundred. The Buddha visited Uruvela-Kassapa and took lodging for the night where the sacred fire was kept, in spite of Kassapa's warning that the spot was inhabited by a fierce Naga [Serpant daemon]. The Buddha, by his magical powers, overcame, first this Naga and then another, both of whom vomited fire and smoke. Kassapa being pleased with this exhibition of iddhi-power, undertook to provide the Buddha with his daily food. Meanwhile the Buddha stayed in a grove near by, waiting for the time when Kassapa should be ready for conversion ... The Buddha spent the whole rainy season there, performing, in all, three thousand five hundred miracles of various kinds, reading the thoughts of Kassapa, splitting firewood for the ascetics' sacrifices, heating stoves for them to use after bathing in the cold weather, etc. Still Kassapa persisted in the thought, "The great ascetic is of great magic power, but he is not an arahant like me." Finally the Buddha decided to startle him by declaring that he was not an arahant, neither did the way he followed lead to arahantship. Thereupon Kassapa owned defeat and reverently asked for ordination. The Buddha asked him to consult with his pupils, and they cut off their hair and threw it with their sacrificial utensils into the river and were all ordained. Nadi-Kassapa and Gaya Kassapa came to inquire what had happened, and they, too, were ordained with their pupils. At Gayasisa the Buddha preached to them the Fire Sermon [The All, Beggars, is On Fire!], and they all attained arahantship.
From Gayasisa the Buddha went to Rajagaha with the Kassapas and their pupils, and in the presence of Bimbisara and the assembled populace Uruvela-Kassapa declared his allegiance to the Buddha.
Uruvela-Kassapa was so called partly to distinguish him from other Kassapas and partly because he was ordained at Uruvela. At first he had one thousand followers, and after he was ordained by the Buddha all his followers stayed with him and each of them ordained a great number of others, so that their company became very numerous.
... According to Tibetan sources, Kassapa was one hundred and twenty years old at the time of his conversion.
From the Psalms:
Beholding all the wondrous works achieved
By the high powers of glorious Gotama,
At first, natheless, myself I humbled not,
Being deceived by envy and by pride.
But He, Driver of men, who knew my thought
And my intent, took me at length to task.
Thereby anguish befell me, I was seized
By thrill mysterious, hair-raising dread.
And then the gifts that erst accrued to me
As famed ascetic poor and worthless seemed.
All these I thereupon esteemed as nought,
And in the Conqueror's Order was enrolled.
Once well content with sacrifice, 'bove all
Concerned within these worlds once more to live
Now have I set myself to extirpate
All passion, all ill will, illusion too.
How erst I lived I know; the heavenly eye,
Purview celestial, have I clarified;
Power supernormal, reading others' thought,
Hearing ineffable, have I achieved.
And the great Quest for which I left the world,
Forsaking home, a homeless life to lead,
Even that quest, that high reward I've won,
For every fetter now is broken down.