mad-guṇa-śruti-mātreṇa
mad-guṇa-śruti-mātreṇa mayi sarva-guhāśaye |
mano-gatir avicchinnā yathā gaṅgāmbhaso’mbudhau ||
lakṣaṇaṁ bhakti-yogasya nirguṇasya hy udāhṛtam |
ahaituky avyavahitā yā bhaktiḥ puruṣottame ||
(Śrīmad Bhāgavatam: 3.29.11–12; cited in Bhakti-rasāmṛta-sindhu: 1.2.13–15; Bhakti Sandarbha: 234)
“‘[Kapiladeva to Devahūti:] Bhakti which is an uninterrupted, causeless, and unobstructed flow of the mind—solely because of hearing my qualities—towards me, the Supreme Person, who dwells in the hearts [lit., “caves”] of all, like [the flow of] the water of the Gaṅgā towards the ocean, is said to be the characteristic of nirguṇa-bhakti-yoga.”