This sutta recurs at SN 35.88, with slight differences in the opening and closing. In addition to two discourse parallels in Chinese, the popularity of this narrative is attested by its appearance in later texts such as the Mūlasarvāstivāda Vinaya and the Divyāvadāna, as well as in artworks (see Anālayo, Comparative Study, vol. ii, p. 828).

This Puṇṇa is to be distinguished from the Koliyan ascetic of MN 57 and the son of Mantāṇī of MN 23. His only other appearance is his Theragāthā verse at Thag 1.70.

The idea of a “retreat” as understood today was popularized in the 20th century. In early times, it seems, when an individual monastic felt they were ready, they would approach the teacher seeking advice for their retreat.

The commentary says that Puṇṇa was in fact born in Sunāparanta, specifically the trading port of Suppāraka, which is modern Nallasopara north of Mumbai on India’s west coast. Sunāparanta is otherwise known as Aparanta (“Far West”, Bv 29:17.2). Puṇṇa’s choice was far-sighted, as from the time of Ashoka, Suppāraka became a major trading center with ports in India and lands west as far as Mesopotamia, Egypt, Eastern Africa, and Rome. A fabulous tale of such trading voyages is told in Ja 463.

This is in reference to the notorious story of Migalaṇḍika in Bu Pj 3, told more briefly in SN 54.9. Several monks, meditating improperly on the unattractiveness of the body, sought death as the way out. In response, the Buddha taught mindfulness of breathing, which is “peaceful and sublime, a deliciously pleasant meditation”. | The idiomatic phrase satthahāraka is difficult. The obvious reading is to take sattha as “knife”, the meaning it has in the preceding sentence. However, that yields the sense “knife-bringer”, “assassin”, whereas the use of idaṁ in MN 145:5.32 shows it must be neuter, i.e. it is a thing not a person. Richard Gombrich suggests we read sattha here as equivalent to Sanskrit śvasita, “breathing, life” (see Brahmali’s note on Bu Pj 3:2.49.1), yielding the sense “life-taker”, “breath-stealer”, “deadly weapon”. This agrees with the Vinaya commentary, which explains, “What does it take? Life.” (Kiṃ harati? Jīvitaṁ). Since this idiom is only used in the context of suicide, I call it “suicide weapon”, and the verbal form “commit suicide”.

The parallel passage at SN 35.88:18.7, says rather that he passed away in that same rainy season.