SB 7.1.48

śrī-yudhiṣṭhira uvāca
vidveṣo dayite putre
 katham āsīn mahātmani
brūhi me bhagavan yena
śrī-yudhiṣṭhiraḥ uvāca — Mahārāja Yudhiṣṭhira said; vidveṣaḥ — hatred; dayite — for his own beloved; putre — son; katham — how; āsīt — there was; mahā-ātmani — the great soul, Prahlāda; brūhi — please tell; me — unto me; bhagavan — O exalted sage; yena — by which; prahlādasya — of Prahlāda Mahārāja; acyuta — to Acyuta; ātmatā — great attachment.
Mahārāja Yudhiṣṭhira inquired: O my lord, Nārada Muni, why was there such enmity between Hiraṇyakaśipu and his beloved son Prahlāda Mahārāja? How did Prahlāda Mahārāja become such a great devotee of Lord Kṛṣṇa? Kindly explain this to me.

All the devotees of Lord Kṛṣṇa are called acyutātmā because they follow in the footsteps of Prahlāda Mahārāja. Acyuta refers to the infallible Lord Viṣṇu, whose heart is always infallible. Because the devotees are attached to the Infallible, they are called acyutātmā.

Thus end the Bhaktivedanta purports of the Seventh Canto, First Chapter, of the Śrīmad-Bhāgavatam, entitled “The Supreme Lord Is Equal to Everyone.”