Five ages ago there was an inferior goddess named Satyeshwari. Satyeshwar was her brother. Satyeshwar died on the day before Nagpanchami. In grief of her brother`s death she did not eat any food.
Hence females observe fast on that day for their brothers for brother`s longevity, acquiring of various weapons and for him to come out from sorrows and dangers safely is also one of the reason for observing the fast. If the sister calls out to god for her brother on the previous day of Nagpanchami, then the brother gets 75% benefit and is also protected. The worshipper must get up early before sun rise on Nag Panchami Day. After the bath and daily routine in the morning, the house should be purified by sprinkling Gangajal or the water from some sacred river.
Establish an idol or picture of lord Shiva and Nag Deva in Eshan Kona. Sit quietly on the ground and take Sankalp of the fast. After the Sankalp, Nag Dev should be worshipped by offering milk- Durva, Kusha, scent, flowers, grains of rice and sweets. On both side of the entrance door of the house, five sketches of Nag Devta should be made with Cow Dung or red powder. In case,
if cow dung is not possible, Geru (red clay powder) could be used. The worshipper must keep fast for the entire day. Serve Nag Dev in the temple. By doing this pooja the auspiciousness enhances in one's life. Reciting Nag strotra or Nag mantra on this day is also considered very auspicious.
The following mantra should be recited for 11, 21 or 108 times.
If possible three malas of this mantra should be recited Om Kurukulye Hum Phat Swaha” The above mantra is considered as the best method to remove Kal Sarpa dosha from the kundali. By reciting this mantra on regular basis the affected person gets released of all the negative influences cast by this dosha. Scent or perfume should be used in the worshipping of Nag Dev on this day.
Food cooked in oil should not be consumed during the fast. According to one belief those who are not bearing fast should take food cooked at the prior day.
Food items other than fast items should not be cooked on this day. The fasting gets completed after the sun set by offering Prasadam (Kheer) to Nag Dev. The worshipper then could open fast by consuming Kheer and the sweet food.