Hiranyakashipu was a powerful Demon king who worshiped Lord Brahma for a Boon.
Brahma granted him the boon because of his hard Tapasya. Hiranyakashipu asked for such a boon which made it impossible for any one to kill him. Hiranyakashipu asked for the boon that should not be killed during day or night, neither on earth nor in sky, neither by man nor by animal, neither in nor outside home, neither by Astra nor by shastra (tools and weapons).
After attaining such a boon Hiranyakashipu attacked Havens and earth and demanded people to worship him. Hiranyakashipu’s Son Prahlada was a devotee of Lord Vishnu . Despite of all his efforts Hiranyakashipu could not make his son to hate Lord Vishnu. Hiranyakashipu ordered to kill Prahlada . Prahlada was poisened, trembled by elephants, throun between hungry snakes, even Hiranyakashipu’s sister Holika (click here to know the story of Prahlad and Holika) could not kill him.
Hiranyakashipu asked Prahlada if he truly believe in Vishnu then he must ask Vishnu to come out of a Pillar in front of them.
Hearing Prahlada’s Pray lord Vishnu took the Avatar of Narshimha and came out of that pillar . He killed Hiranyakashipu at the Dusk (neither day nor night) on the steps of the porch of his house ( neither inside nor outside the house) by restraining him on his lap (neither in sky nor on earth) and mauling him with his claws (neither astra nor shastra). . Narshimha is half men half lion(neither man nor animal).