When one develops an unflinching sense of ownership or possessiveness in relation to Lord Visnu, or, in other words, when one thinks Visnu and no one else to be the only object of love, such an awakening is called bhakti (devotion)

Expressions researched:
"When one develops an unflinching sense of ownership or possessiveness in relation to Lord Viṣṇu, or, in other words, when one thinks Viṣṇu and no one else to be the only object of love, such an awakening is called bhakti"

Sri Caitanya-caritamrta

CC Madhya-lila

When one develops an unflinching sense of ownership or possessiveness in relation to Lord Viṣṇu, or, in other words, when one thinks Viṣṇu and no one else to be the only object of love, such an awakening is called bhakti [devotion] by exalted persons like Bhīṣma, Prahlāda, Uddhava and Nārada.

CC Madhya 23.8, Translation and Purport

When one develops an unflinching sense of ownership or possessiveness in relation to Lord Viṣṇu, or, in other words, when one thinks Viṣṇu and no one else to be the only object of love, such an awakening is called bhakti [devotion] by exalted persons like Bhīṣma, Prahlāda, Uddhava and Nārada.

This verse, quoted from the Nārada-pañcarātra, is found in the Bhakti-rasāmṛta-sindhu (1.4.2).