This is celebrated as the day that the deity Vishnu enters a yogic sleep (yoga nidra)[7] on his serpent, Shesha, for a period of four months and wakes up on Prabodhini Ekadashi.

The story is recalls how Shiva saved creation by drinking poison called "halahala" which emerged from the ocean while it was being churned by the asuras (demons) and devas (demigods).

Penance, austerities, religious observances, recital of mantras, bathing in holy rivers, performing sacrifices, and charity are prescribed.

[11] A number of Hindus, particularly those following the Vaishnava tradition, refrain from eating meals that are oily, salty, sweet or that contain onion or garlic, and eggplant during this period.

[15] Wandering monks such as mendicants and ascetics in Jainism, believe that during the rainy season, countless bugs, insects and tiny creatures that cannot be seen in the naked eye take birth massively.

[16] These monks, who generally do not stay in one place for long(59 nights for females, 29 nights for males), observe their annual 'Rains Retreat' during this period, by living in one place during the entire period amidst lay people, observing a vow of silence (mauna), meditation, fasting and other austerities, and also giving religious discourses to the local public.

[citation needed] During the four-month rainy-season period, when the mendicants must stay in one place, the chief sadhu of every group gives a daily sermon (pravacana, vyakhyana), attended mostly by women and older, retired men, but on special days by most of the lay congregation.

[citation needed] Gautama Buddha stayed at the royal garden of King Bimbisara of Rajgir, whom he had recently converted, for the period of Chaturmasya and gave sermons: this practice is followed by monks to this day.

Another reason for ascetics to stay in one place during the rainy season is that the tropical climate produces a large number of insects, which would be trampled by travelling monks.