Without water
From Sanskrit 'nir' (without) + 'jala' (water).
The strictest form of fast: no food and no water. Karva Chauth and Nirjala Ekadashi are the best-known observances kept this way.
Meaning, Origin, Fasting and Parana
The sacred story from the Brahmanda Purana of the Amla tree (Indian Gooseberry) created from Lord Vishnu's tears, granting salvation even to a sinful hunter in Phalguna Shukla Paksha.
A guide to Ekadashi Vrat: Ekadashi Devi's origin, the three modes of fasting, foods to avoid, puja vidhi, and the rules of Dwadashi Parana and Hari Vasara.
The story from the Padma Purana of Malyavan and Pushpavati liberated from a ghostly demonic curse by observing Jaya Ekadashi in Magha Shukla Paksha.
The Padma Purana katha of Lalit and Lalita, where a wife's Kamada Ekadashi fast and surrendered merit freed her husband from a demonic curse.
The Vrat for a Husband’s Long Life and Wellbeing