Once there was a king called Hiranyakashipu. His son is Prahalad.Prahalad was a great devotee of Lord Narayana. He always prays Vishnu and keeps chanting " Hari Hari "
Hiranyakashipu, the king did penance and God granted him a boon that he should not be killed by any human being, nor by any weapon, nor in the morning/afternoon/ night and also not inside/outside the palace . So with this boon the king became a cruel king .
He started telling his people that there is no other God other than himself. So everone should pray him only.
Son, Prahalad himself , refused to obey his dad in this regard.
Inspite of his dad's orders Prahalad continued his prayers for Lord Vishnu.
At this , the king got angry and he ordered his son ,Prahalad to be killled by elephants.
But Lord Vishnu saved Prahalad from elephants. Then the King threw him into the sea and even threw him into the fire.
But Lord Vishnu being happy with the prayers of Prahalad , saved him from all these dangers.
Looking at all this the king was very angry with his son.
One evening Prahalad was praying Lord Vishnu , chanting " Hari Hari ".
On hearing this , the King dashed into the room. He was very angry and shouted at Prahalad "My son. I am repeatedly telling you not to worship Vishnu but you keep
on chanting "Hari, Hari ". Can you tell me where your Hari is?"
Immediately, Prahald replied politely, " Father, Hari is everywhere. I cannot show a place where Hari is not present."
At this the king got still more angry and shouted at him pointing to a pillar in the palace "Do you mean to say that your Hari is inside this pillar?"
Prompt came the reply, " YES ".
Immediately the King asked his servants to bring his " gatha " ( a weapon used for fighting). The servants rushed for it and gave it to him.
The king started banging the pillar with the "gatha".
At one point , the pillar broke open and out came Lord Vishnu, but not in his usual form
He came in the form of " Narasimha " , with a human body and a lion's face and with long nails .
The King was stunned . Lord Narasimha immediately barged upon the king and took him in his hands and moved towards the gateway .
He sat right there on the gateway ,put the king on the lap and with his long nails tore the king and killed him . That was the end of king Hiranyakashipu.
God also took care that his granted boon was not overlooked.
That was the reason why Lord Vishnu took the unique form of Lord Narasimha (Neither a human being nor an animal).
He killed him with his nails without using any weapon .
Also the king was killed neither inside nor outside but on the steps of the gateway , and also only in the evening thus fulfilling the boon.
Because of his faith in God Prahalad attained a special place in Vaikunt (Abode Of Lord Vishnu) after his death.
image courtesy --google.