SB 7.10.13
bhogena punyam kusalena papam
kalevaram kala-javena hitva
kirtim visuddham sura-loka-gitam
vitaya mam esyasi mukta-bandhah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
My dear Prahlada, while you are in this material world you will exhaust all the reactions of pious activity by feeling happiness, and by acting piously you will neutralize impious activity. Because of the powerful time factor, you will give up your body, but the glories of your activities will be sung in the upper planetary systems, and being fully freed from all bondage, you will return home, back to Godhead.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Srila Visvanatha Cakravarti Thakura says: evam prahladasyamsena sadhana-siddhatvam nitya-siddhatvam ca naradadivaj jñeyam. There are two classes of devotees — the sadhana-siddha and the nitya-siddha. Prahlada Maharaja is a mixed siddha; that is, he is perfect partly because of executing devotional service and partly because of eternal perfection. Thus he is compared to such devotees as Narada. Formerly, Narada Muni was the son of a maidservant, and therefore in his next birth he attained perfection (sadhana-siddhi) because of having executed devotional service. Yet he is also a nitya-siddha because he never forgets the Supreme Personality of Godhead.
The word kusalena is very important. One should live in the material world very expertly. The material world is known as the world of duality because one sometimes has to act impiously and sometimes has to act piously. Although one does not want to act impiously, the world is so fashioned that there is always danger (padam padam yad vipadam). Thus even when performing devotional service a devotee has to create many enemies. Prahlada Maharaja himself had experience of this, for even his father became his enemy. A devotee should expertly manage to think always of the Supreme Lord so that the reactions of suffering cannot touch him. This is the expert management of papa-punya — pious and impious activities. An exalted devotee like Prahlada Maharaja is jivan-mukta; he is liberated even in this very life in the material body.