Shree Nrusinh Jayanti
Vaishakh Sud 14
Manifestation as of Shri Krshna's mouth (mukharvind), story of Pralhad & his father Hiranyakashyapu.
Shri Mahaprabhuji wants to preach us that if we have the same love for God as Pralhad had, then God will abide to the wishes of the devotee & will manifest Himself in the house of the devotee to respond to his sentiment of devotion. This is the real secret behind "Bhavpratishtha" (making Thakorji 'Pushta') of our deity. "Enam udhdharishyami" eti tatha mrudadehe pradurbhutaha pratimarganusaren". According to this quotation, God's manifestation depends on the wish/anxiety of the devotee; otherwise Harinyakashyapu could have been killed without manifestation. But to justify Pralhadji's faith in Him, He came out of the pillar as Nrusinha Avataar. In short from Aksharbramhavakta to Purushottamta His Mahatmya (importance) of this festival.
source: pushtimarg.net