There are exceptional cases where persons achieved devotion through the Lord’s direct mercy, but whether it’s the Lord’s mercy of the mercy of the pure devotee, mercy is required for the development of bhakti.The other part of the formula is that we have to become qualified receptacles for the mercy. We have to seek mercy by hearing the divine instructions on how to please Krishna. By hearing those instructions and acting upon them, we become qualified for further mercy.The Bhagavatam also explains that by serving devotees who are free of vice, we are rendering a great service. By that service, our attraction to hearing and chanting Krishna-katha will increase.Therefore the Bhagavatam states that both hearing and Vaisnava seva must be there.
Lectures from a disciple Vol 1, Pg 324-325 last paragraph onwards.