CC Madhya 25.137
- na sādhayati māṁ yogo
- na sāṅkhyaṁ dharma uddhava
- na svādhyāyas tapas tyāgo
- yathā bhaktir mamorjitā
na—never; sādhayati—causes to remain satisfied; mām—Me; yogaḥ—the process of control; na—nor; sāṅkhyam—the process of gaining philosophical knowledge about the Absolute Truth; dharmaḥ—such an occupation; uddhava—My dear Uddhava; na—nor; svādhyāyaḥ—study of the Vedas; tapaḥ—austerities; tyāgaḥ—renunciation, acceptance of sannyāsa, or charity; yathā—as much as; bhaktiḥ—devotional service; mama—unto Me; ūrjitā—developed.
“[The Supreme Personality of Godhead, Kṛṣṇa, said:] ‘My dear Uddhava, neither through aṣṭāṅga-yoga [the mystic yoga system to control the senses], nor through impersonal monism or an analytical study of the Absolute Truth, nor through study of the Vedas, nor through austerities, charity or acceptance of sannyāsa can one satisfy Me as much as by developing unalloyed devotional service unto Me.’
This is a quotation from Śrīmad-Bhāgavatam (SB 11.14.20). For an explanation see Adi-līlā, Chapter Seventeen, text 76.