Śrī Caitanya-caritāmṛta - Madhya-līlā 20.137

"“[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."

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Śrī caitanya-caritāmṛta Madhya 20.137