Bhakti-rasāmṛta-sindhu .3.57
Blended reading (Sanskrit + English inline)
If, however, it is seen that a person has developed a high standard of devotion without having undergone even the regulative principles, it is to be understood that his status of devotional service was achieved in a former life. For some reason or another it had been temporarily stopped, most probably by an offense committed at the lotus feet of a devotee. Now, with a good second chance, it has again begun to develop. The conclusion is that steady progress in devotional service can be attained only in the association of pure devotees.
Sādhana refers to all the causes of bhāva: sādhana-bhakti, the mercy of Kṛṣṇa and the mercy of the devotee. Īkṣā refers to the knowledge gained through scriptures. Sometimes, bhāva appears suddenly without knowledge of scriptures, and without sādhana, mercy of Kṛṣṇa or mercy of the devotee. It is seen and verified to be real bhāva (īkṣyate). One should then infer sādhana from a previous life, as in the case of Vṛtrāsura and others.
My note
Source: vedabase.io