The Vishnu Sahasranama is a Sanskrit hymn containing a list of the 1,000 names of Vishnu, one of the main deities in Hinduism and the Supreme God in Vaishnavism. It is one of the most sacred and popular stotras in Hinduism. From Wikipedia
Devotees prepare for fasting, prayer, and rituals as Drik Panchang confirms tithi and parana timings for this sacred day dedicated to Lord Vishnu.