增壹阿含經 24.5.p155

24.5.p155

They followed the river downstream to where the ascetic named Nadī Kāśyapa lived on the riverbank. Nadī Kāśyapa saw all their implements of magical incantation floating in the water. He then thought, “What? Did my older brother drown in the river?” Nadī Kāśyapa then led his 300 disciples upstream searching for his brother’s body. He saw the Bhagavān sitting under a tree from a distance, surrounded in front and behind by Great Kāśyapa and his 500 disciples. He said, “What’s the reason for this marvel? A man who was once a teacher now is a disciple! Why did my older brother become a disciple of that ascetic that he’s accompanying?”