A brahmin. He once visited the Buddha at Sāvatthī and asked him whether the five sense-faculties, which were of different scope and range, had any common ground of resort. The Buddha replies that the mind is their common resort and, in answer to further questions, explains that there is nothing beyond Nibbāna; that the holy life has Nibbāna for its ending.
When the brahmin, greatly pleased with the Buddha’s teaching, goes away, the Buddha tells the monks that Uṇṇābha has become an anāgāmī and would, therefore, after death, no longer return to this world. SN.v.217f.
The same Nikāya SN.v.272f. records a visit of Uṇṇābha to Ānanda at Kosambī. He asks Ānanda what is the aim of holy life and, on being told that it is the abandoning of desire by means of jhāna, suggests that it would be a task without end. But Ānanda, by means of an illustration, explains how the task does come to an end, and Uṇṇābha expresses great satisfaction with the answer. Perhaps this refers to another brahmin of the same name.