A Paribbājaka. He was the teacher of Brahmadatta. It was the discussion between these two, in the Ambalaṭṭhikā park, regarding the virtues of the Buddha, his Dhamma and his Order, which led to the preaching of the Brahmajāla Sutta. DN.i.1
He was born in Sāvatthī in a family of cemetery keepers. Converted by the preaching of his friend, the Thera Sopāka, he entered the Order and attained arahantship.
In the time of Padumuttara Buddha he was a brahmin, named Varuṇa, who left his ten children and became an ascetic in the forest. There he met the Buddha and his monks and gave them fruit. He belonged to a khattiya family in the time of Kassapa Buddha, but through pride of birth and learning used to detract his colleagues hence his birth in a low caste in his last life. Thag.32