A thera. He was the son of a caravan guide at Vaḍḍhagāma (v.l. Veḷugāma) in Avanti. By correspondence he became the unseen friend of Citta-gahapati of Macchikāsaṇḍa. The latter once sent him a letter regarding the virtues of the Buddha, and Isidatta, being pleased with the account given of the Buddha’s religion, entered the Order under Mahā-Kaccāna and in due course became an Arahant. Later, with Mahā-Kaccāna’s leave, he visited the Buddha in the Majjhimadesa and was warmly received by him (ThagA.i.238). A verse uttered by Isidatta, in response to the Buddha’s enquiry regarding his welfare, is recorded in the Theragāthā (v.120).

Isidatta had been a householder in the time of Vipassī Buddha and once, having seen the Buddha walking along the street and being pleased with his demeanour, he gave him an āmoda-fruit (ThagA. loc. cit.) He is, probably, identical with Amodaphaliya Thera of the Apadāna (ii.447).

According to the Saṃyuttanikāya (iv.283-8, also AA.i.210), Isidatta was once staying with a number of senior monks at Macchikāsaṇḍa in the Ambāṭaka 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 taught 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. However, that same day Isidatta left Macchikāsaṇḍa and never returned. Because, says Buddhaghosa (AA.i.210), he did not wish to stay after having been recognised.