There was once a great Asura, who was in a great rage.  His brother Hiranyaksa had just been killed by the incarnation of Vishnu known as Lord Varaha. Thus he became very determined to become the emperor of the entire universe. In order to increase his power, he performed very powerful austerities. This penance was so severe that it disturbed the Devas. In fact, the Devas requested Lord Brahma to stop him. Lord Brahma, therefore decided to pacify him by granting him his wish.

"Please grant that I not be killed by any created living being," commanded Hiranyakasipu, "that I not die inside or outside any residence, during the daytime or night, nor on the ground or in the sky; that I not be killed by any being created by you, nor by any weapon, nor by any human being or animal indeed that I not meet death from any entity, either living or non-living; that I have no competitor; that I have sole lordship over all living entities and presiding deities, and that I acquire all mystic powers."

After Brahma had granted him all these requests, Hiranyakasipu very swiftly conquered all the planets in the universe, took up residence in the lavish palace of King Indra, and forced the Devas to bow down to his feet. Intoxicated by power, Hiranyakasipu ruled the universe very severely.

During this time his queen, Kayadhu, returned to the palace of her husband and bore him a son, Prahlada. He was a reservoir of all transcendental qualities because he was an pure devotee of Lord Vishnu. Determined to understand the Absolute Truth, he had full control over his senses and mind He was kind to all living creatures and the best friend of everyone. Toward respectable persons he behaved just like a menial servant, to the poor he was like a father, and to his equals he was always like a sympathetic brother. Always very humble, he considered his teachers and spiritual masters to be as good as the Lord Himself. Indeed, he was completely free of and pride that might have arisen from his good education, riches, beauty, and aristocratic birth.

Hiranyakasipu wanted to raise his son to be a powerful Asura, but Prahlada only wanted to learn about devotional service to Lord Visnu. After Prahlada attended school for some time, Hiranyakasipu took him on his lap and affectionately inquired, "My dear son, please tell me about your favorite subject in school."

Fearlessly, Prahlada said, "Hearing (sravanam) and chanting (kirtanam) about the holy name, form, qualities, paraphernalia, and pastimes of the Supreme Lord; remembering (smaranam) them; serving the lotus feet of the Lord (pada-sevanam); offering the Lord respectful worship with sixteen types of paraphernalia (arcanam); offering prayers to the Lord (vandanam); becoming His servant (dasyam); considering the Lord one’s best friend (sakhyam); and surrendering to Him (atma-nivedanam, in other words, serving Him with body, mind and words); these nine processes are known as pure devotional service, and I consider anyone who has dedicated his life to service of Lord Visnu through these nine methods to be the most learned person to be the most learned person, for he has acquired complete knowledge."

Blinded by anger, Hiranyakasipu threw Prahlada from his lap onto the ground. "Servants! Take him away and kill him at once!" he screamed. However, Prahlada just sat silently and meditated on Lord Vishnu and nothing the Asuras did caused him any harm. Hiranyakasipu became very anxious about what to do next.

"You say there is a being superior to me," said Hiranyakasipu, "but where is He? If He is present everywhere, then why is He not present in this pillar you see before you? Do you think He is in this pillar?"

"Yes," Prahlada answered, "He is there."

Hiranyakasipu, in great anger, struck the pillar with his mace and roared, "Then let's see if he dares to come out and fight me!"  Then from within the very pillar that he had singled out came a wonderful half-man, half-lion form never before seen. The Lord’s form was extremely fearsome because of His angry eyes, which resembled molten gold; His shining mane, which expanded the dimensions of His fearful face; His deadly teeth; and His razor-sharp tongue. Lord Narasimha then proceeded to battle with Hiranyakasipu.

Finally at twilight, Lord Narasimha captured Hiranyakasipu and placed him in His lap on the doorway of the assembly hall and ripped the Asura to pieces with his hands.  The execution took place neither inside nor outside, but in the doorway; neither on land nor in sky, but on the Lord’s lap; neither during the day nor during the night, but at twilight; neither by man, beast, or Deva nor by any created being; and not by any weapon, but by the Lord's own lotus hand, relieving the whole universe of Hiranyakasipu’s demonic activities.

Having been protected by the Lord, Prahlada Maharaja offered many prayers in a voice that faltered with love to calm the Lord Narasimha who was still very angry in the aftermath of his fight:

"My dear Lord Nrsimhadeva, please, therefore, allow Your angry feature to diminish, now that my father Hiranyakasipu has been killed.  People will always remember this incarnation, for it frees them from fear."

Adapted from Swami Prabhupada's translation (http://www.avatara.org).