SB 7.5.43-44

dig-gajair dandaśūkendrair
 abhicārāvapātanaiḥ
māyābhiḥ sannirodhaiś ca
 gara-dānair abhojanaiḥ
hima-vāyv-agni-salilaiḥ
 parvatākramaṇair api
na śaśāka yadā hantum
 apāpam asuraḥ sutam
cintāṁ dīrghatamāṁ prāptas
 tat-kartuṁ nābhyapadyata
Synonyms: 
dik-gajaiḥ — by big elephants trained to smash anything under their feet; danda-śūka-indraiḥ — by the biting of the King’s poisonous snakes; abhicāra — by destructive spells; avapātanaiḥ — by causing to fall from the top of a mountain; māyābhiḥ — by conjuring tricks; sannirodhaiḥ — by imprisonment; ca — as well as; gara-dānaiḥ — by administering poison; abhojanaiḥ — by starving; hima — by cold; vāyu — wind; agni — fire; salilaiḥ — and water; parvata-ākramaṇaiḥ — by crushing with big stones and hills; api — and also; na śaśāka — was not able; yadā — when; hantum — to kill; apāpam — who was not at all sinful; asuraḥ — the demon (Hiraṇyakaśipu); sutam — his son; cintām — anxiety; dīrgha-tamām — long-standing; prāptaḥ — obtained; tat-kartum — to do that; na — not; abhyapadyata — achieved.
Translation: 
Hiraṇyakaśipu could not kill his son by throwing him beneath the feet of big elephants, throwing him among huge, fearful snakes, employing destructive spells, hurling him from the top of a hill, conjuring up illusory tricks, administering poison, starving him, exposing him to severe cold, winds, fire and water, or throwing heavy stones to crush him. When Hiraṇyakaśipu found that he could not in any way harm Prahlāda, who was completely sinless, he was in great anxiety about what to do next.