Katha (Story) of Monday fast (Somvar vrat) Sixteen Somvar Vrat Legend Certain Hindu women fast for sixteen Mondays in a row to please Shiva. There are lots of myths and mythology concerning why this fast is observed. Based on some communities, this is the fast that Mata Parvati had kept so as to have Shiva as her husband. That’s the reason young girls observe this fast so they might have a companion like Lord (bhagawan) Shiva..