According to Hindu Panchang, the fast of Narsingh Jayanti is celebrated on the Chaturthi Tithi of Shukla Paksha of Vaishakh month. According to the stories mentioned in the Agni Purana, on this holy day, Lord Vishnu incarnated as Narsingh to protect the devotee Prahlada. Because of which this day is celebrated with great pomp and gaiety as Lord Narsingh's birth anniversary. The fast story of Lord Narsingh Jayanti is as follows-
According to the legend, to avenge the death of his brother, Raksharaj Raj Hiranyakashipu, after doing austerity, pleased Brahmaji and Shiva and received the boon of being invincible from him. As soon as he got a boon, he started persecuting the subjects with arrogance and started torturing and torturing them in various ways. Due to which people used to remain extremely sad. These days, Kayadhu, Hiranyakashipu's wife, gave birth to a son, named Prahlada. Even after being born into the demon clan, Prahlada had a deep affection from Sri Hari devotion since childhood.
Hiranyakashipu made many unsuccessful attempts to remove Prahlada's mind from Bhagavad bhakti, but he could not succeed. Once, with the help of his sister Holika, he tried to burn her in the fire, but Prahlada felt desolate due to the immense grace of God. Finally one day he attempted to kill Prahlada with a sword, then Lord Narasimha appeared from the pillar and, taking Hiranyakashipu on his thighs, tore his chest with his fingernails and protected his devotee.
According to the devotees, if one observes fast on this day, worships Lord Narasimha with reverence and devotion, then he gets free from the sins of all births and attains the supreme abode of the Lord.