Śiva's Day — Sāwan Somvār, Solah Somvār and Pradoṣ Vrat

Somavāra — Monday — is Soma's day, and Soma is the moon. The tradition's link to Śiva runs through the same image this series has already used once, in passing, to describe Śivarātri: Śiva as Candraśekhara, the crescent moon caught in his matted hair. That is folk-etymological connective tissue, not a Purāṇic prescription assigning Monday to Śiva by name — worth saying plainly rather than dressing it up as more textually settled than it is. What the Purāṇas do prescribe, in some detail, are three genuinely separate observances that have all come to sit on this one weekday: a month of Mondays, a vow of sixteen Mondays, and a twice-monthly evening fast that isn't tied to Monday at all. This essay keeps all three distinct rather than folding them into one generic "Monday fast for Śiva."

Śrāvaṇ (also Sāwan), roughly July–August, is held to be Śiva's own month, and every Monday within it is kept as a fast across most of North and Central India. The Purāṇic anchor for the month's sanctity is the same Samudra Manthan — the churning of the cosmic ocean — that the next essay in this series returns to for Mahā Śivarātri itself: the Skanda and Bhāgavata Purāṇas tell of a lethal poison, hālāhala, rising from the churned ocean and threatening all creation, until Śiva drinks it and holds it in his throat rather than swallowing it, turning the throat blue and earning him the name Nīlakaṇṭha — the blue-throated one. The living ritual response to that story is direct: worshippers cool the poison-scorched god with offerings of water and milk poured over the liṅga, an act named jalābhiṣeka, kept with particular intensity through Śrāvaṇ and most visibly in the Kāṅvar Yātrā, where pilgrims carry Ganges water on foot, sometimes for hundreds of kilometres, to pour over a Śiva shrine at journey's end.

A separate, self-contained vow: sixteen consecutive Mondays of fasting, worship and the recitation of the Solah Somvār vrata-kathā, most often begun in Śrāvaṇ though the tradition doesn't require it. The Śiva Purāṇa is named, in the vrata-guide literature this essay has consulted, as the text in which Śiva himself instructs Pārvatī in the vow — a detail worth flagging honestly rather than treating as settled: this essay has traced the claim to named secondary vrata-kathā compilations rather than a critical edition of the Purāṇa, the same limitation this series has flagged before. What makes the vow worth telling is its own internal mirror: legend holds that Pārvatī undertook this same sixteen-Monday fast herself, to win Śiva as her husband — so a devotee keeping it today, most often praying for a good marriage or a settled household, is repeating the goddess's own vow rather than merely petitioning her. The fast concludes with an udyāpan — a closing ritual marking the vow fulfilled, distinct from simply stopping on the sixteenth week.

Unrelated to Monday by name, Pradoṣ Vrat is kept on Trayodaśī, the thirteenth lunar day, in both fortnights of every month — roughly twenty-four times a year, more in a leap month — and is named in both the Śiva and Skanda Purāṇas. Pradoṣa itself reads as pra (great, exceeding) plus doṣa (twilight, the dusk hour): the great or sacred twilight, and worship is timed specifically to sandhyā kāla, the threshold window between day and night, rather than to the fast's daylight hours the way most vratas in this series are structured. Regional and devotional practice further names Pradoṣ days by the weekday they fall on — Som Pradoṣ on a Monday folding this fast back into Śiva's day proper, Bhauma Pradoṣ on a Tuesday held especially potent for debt and obstacle-removal, Śani Pradoṣ on a Saturday drawing in Śani's own association with that day. The result is a fast that can, in a given month, land on Monday and effectively merge with the observances above, or land on any other day and stand entirely apart from them.

The cross-tradition disagreements this series named at length in its first essay — the Sikh Rahit Maryādā's rejection of fasting tied to lunar phases by name, the Ārya Samāj's critique of Purāṇic vrata-and-kathā ritualism as a form, Jainism's and Buddhism's rejection of Vedic and Purāṇic authority outright — apply to all three fasts here as much as to any other in this series, and this essay doesn't repeat that ground fast by fast.

Return to What Is a Vrata? — the textual foundations of Hindu fasting for the fuller cross-tradition treatment, and for the rest of the fasting series as each piece is added.

• Primary scripture. Śiva Purāṇa, for Solah Somvār as taught by Śiva to Pārvatī; Śiva Purāṇa and Skanda Purāṇa, for Pradoṣ Vrat's merit and observance; Skanda Purāṇa and Bhāgavata Purāṇa, for the Samudra Manthan / Nīlakaṇṭha episode — all consulted via named secondary summaries and vrata-guide compilations rather than critical editions, the same limitation flagged elsewhere in this series.
• Folklore and oral tradition. The Solah Somvār vrata-kathā and Pārvatī's own legendary observance of the fast; the Kāṅvar Yātrā as a living, present-day practice built on the Samudra Manthan story.
• Cross-tradition sources. As cited in this series' first essay — the Gurū Granth Sāhib, the Sikh Rahit Maryādā, and Dayānanda Sarasvatī's Satyārtha Prakāśa — not repeated in full here.