The next Ekadashi in 2023 falls on the coming Sunday of this month - September 10. Known as the "Aja Ekadashi," also known as Ananda Ekadashi, is a day dedicated to Lord Vishnu and his divine consort Goddess Lakshmi.
It is observed on the 11th day of Krishna Paksha in Bhadrapada month. The occasion associates itself with Raja Harishchandra, the king known for his honesty. Religious texts narrate that Sage Gautam suggested the honest king to keep the Aja Ekadashi Vrat when he miserably lost his empire and family.
Originally, the Brahmavaivarta Purana mentions Lord Vishnu stating the importance of this Ekadashi to Yudhisthira. It is believed that observing a fast on this day will forgive one of their sins and let them visit 'Vaikunta' after death.

Devotees believe that offering prayers to Lord Vishnu and visiting His temples on this day brings happiness, prosperity, and liberation. While some keep a complete 'nirjala' (without water) fasting to mark this day, others do it as per one's capacity.
The fast is broken on the next day around sunrise, September 11. The word 'parana' implies to the end a fast. The Ekadashi Parana on Dwadashi Thithi: 06:12 AM to 08:41 AM