Even though a person who has no assets in pious activities performs some good deed, it will have no result. Thus the weapons of the demons had no tangible effects upon Prahlāda Mahārāja because he was a devotee undisturbed by material conditions and fully engaged in meditating upon and serving the Supreme Personality of Godhead, who is unchangeable, who cannot be realized by the material senses, and who is the soul of the entire universe.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
परे ब्रह्मण्यनिर्देश्ये भगवत्यखिलात्मनि । युक्तात्मन्यफला आसन्नपुण्यस्येव सत्क्रियाः
pare brahmaṇyanirdeśye bhagavatyakhilātmani | yuktātmanyaphalā āsannapuṇyasyeva satkriyāḥ
SB 7.5.41