Therefore, O great sage, please give me instruction on the transcendental devotional service of the Lord, so that He who is situated in the heart of everyone can be pleased to impart, from within, knowledge of the Absolute Truth in terms of the ancient Vedic principles delivered only to those who are purified by the process of devotional service.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तत्साधुवर्यादिश वर्त्म शं नः संराधितो भगवान् येन पुंसाम् । हृदि स्थितो यच्छति भक्तिपूते ज्ञानं स तत्त्वाधिगमं पुराणम्
tatsādhuvaryādiśa vartma śaṃ naḥ saṃrādhito bhagavān yena puṃsām | hṛdi sthito yacchati bhaktipūte jñānaṃ sa tattvādhigamaṃ purāṇam
SB 3.5.4