A verse uttered by Isidatta, in response to the Buddha’s enquiry regarding his welfare, is recorded in the Therāgāthā. Thag.120
According to the Saṃyutta Nikāya, SN.iv.283–288 Isidatta was once staying with a number of senior monks at Macchikāsaṇḍa in the Ambātaka grove. Citta-gahapati invited the monks to a meal. On this occasion Citta asked a question regarding the Buddha’s teaching on the diversity of the elements. The chief Elder, being unable to answer, remained silent. Isidatta, though the most junior of the whole company, obtained the chief Elder’s permission, and answered the question to the satisfaction of Citta. Citta likewise asked questions regarding various views, such as the infinity of the world, etc. At the end of the discourse, Citta discovered, by accident, that the Elder who had preached to him was none other than his unseen friend, Isidatta. Delighted with the discovery, he invited Isidatta to spend his time at a Macchikāsaṇḍa, promising to provide him with all requisites. But that same day Isidatta left Macchikāsaṇḍa and never returned.
An equerry or chamberlain of Pasenadi, King of Kosala. Isidatta is always mentioned with Purāṇa.
Isidatta and Purāṇa were once at Sādhuka’ on some business. They heard that the Buddha was having a robe made before starting on his rounds and they waited for an opportunity to talk to him. When the opportunity came they followed the Buddha and told him how glad they always were when he was near them and how sad when he was away on tour. The Buddha preaches to them the glory of the homeless life and urges them to put forth energy. He speaks very appreciatively of their loyalty to him and to his religion and congratulates them on the possession of virtuous qualities, such as sharing all their goods with holy men, a rare quality. SN.348–352
In the Dhammacetiya Sutta, MN.ii.123f. Pasenadi tells the Buddha how impressed he is by the reverence Isidatta and Purāṇa show for the Buddha and his teachings. “They are my carriage-builders,” says the king, “and they depend on me for their livelihood and all their honours, yet these men do not serve me as whole-heartedly as they do the Lord.”
Once the king spent the night in a cramped little house. Isidatta and Purāṇa, who were with him, having spent the best part of the night in discussing the Doctrine, lay down to rest with their heads in the direction in which they thought the Buddha to be, and their feet towards the king!
Isidatta was the uncle of the woman-disciple Migasālā, whose father was Purāṇa. Purāṇa is described as a brahmacāri, but not Isidatta, yet, after death, they were both born in Tusita. Migasālā asks Ānanda how it was that people of different characters could have the same rebirth. AN.iii.348f. AN.v.138f. AN.v.143f.
Isidatta is mentioned by the Buddha among those who had the six qualities that brought realisation of immortality—unwavering loyalty to the Buddha, the Dhamma and the Saṅgha, Ariyan virtue, wisdom and liberation. AN.iii.451