O greatest of all, those whose consciousness is polluted by illusion cannot purify themselves merely by ordinary worship, study of the Vedas, charity, austerity and ritual activities. Our Lord, those pure souls who have developed a powerful transcendental faith in Your glories achieve a purified state of existence that can never be attained by those lacking such faith.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
शुद्धिर्नृणां न तु तथेड्य दुराशयानां विद्याश्रुताध्ययनदानतपःक्रियाभिः । सत्त्वात्मनामृषभ ते यशसि प्रवृद्ध- सच्छ्रद्धया श्रवणसम्भृतया यथा स्यात्
śuddhirnṛṇāṃ na tu tatheḍya durāśayānāṃ vidyāśrutādhyayanadānatapaḥkriyābhiḥ | sattvātmanāmṛṣabha te yaśasi pravṛddha- sacchraddhayā śravaṇasambhṛtayā yathā syāt
SB 11.6.9