SB 7.9.29
mat-prana-raksanam ananta pitur vadhas ca
manye sva-bhrtya-rsi-vakyam rtam vidhatum
khadgam pragrhya yad avocad asad-vidhitsus
tvam isvaro mad-aparo ’vatu kam harami
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
My Lord, O unlimited reservoir of transcendental qualities, You have killed my father, Hiranyakasipu, and saved me from his sword. He had said very angrily, “If there is any supreme controller other than me, let Him save you. I shall now sever your head from your body.” Therefore I think that both in saving me and in killing him, You have acted just to prove true the words of Your devotee. There is no other cause.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In Bhagavad-gita (9.29) the Lord says:
samo ’ham sarva-bhutesu
na me dvesyo ’sti na priyah
ye bhajanti tu mam bhaktya
mayi te tesu capy aham
The Supreme Personality of Godhead is undoubtedly equal to everyone. He has no friend and no enemy, but as one desires benefits from the Lord, the Lord is very pleased to award them. The lower and higher positions of different living entities are due to their desires, for the Lord, being equal to all, fulfills everyone’s desires. The killing of Hiranyakasipu and saving of Prahlada Maharaja also strictly followed this law of the supreme controller’s activities. When Prahlada’s mother, Hiranyakasipu’s wife, Kayadhu, was under the protection of Narada, she prayed for the protection of her son from the enemy, and Narada Muni gave assurance that Prahlada Maharaja would always be saved from the enemy’s hands. Thus when Hiranyakasipu was going to kill Prahlada Maharaja, the Lord saved Prahlada to fulfill His promise in Bhagavad-gita (kaunteya pratijanihi na me bhaktah pranasyati) and to prove true the words of Narada. The Lord can fulfill many purposes through one action. Thus the killing of Hiranyakasipu and the saving of Prahlada were enacted simultaneously to prove the truthfulness of the Lord’s devotee and the fidelity of the Lord Himself to His own purpose. The Lord acts only to satisfy the desires of His devotees; otherwise He has nothing to do. As confirmed in the Vedic language, na tasya karyam karanam ca vidyate: the Lord has nothing to do personally, for everything is done through His different potencies (parasya saktir vividhaiva sruyate). The Lord has multifarious energies, through which everything is done. Thus when He personally does something, it is only to satisfy His devotee. The Lord is known as bhakta-vatsala because He very much favors His devoted servant.