“Devotees of the Supreme Lord experience both happiness and distress — not as consequences of material work but as incidental effects of their loving reciprocation with the Lord. Śrīla Rūpa Gosvāmī, in Śrī Bhakti-rasāmṛta-sindhu, his definitive treatise on the process of devotional service, explains how a Vaiṣṇava is relieved of all karmic reactions, including those that have not yet begun to manifest (aprārabdha), those that are just about to manifest (kūṭa), those that are barely manifesting (bīja) and those that have manifested fully (prārabdha). As a lotus gradually loses its many petals, so a person who takes shelter of devotional service has all his karmic reactions destroyed.
That devotional service to Lord Kṛṣṇa eradicates all karmic reactions is confirmed in this passage of the Gopāla-tāpanī śruti (Pūrva 15): bhaktir asya bhajanaṁ tad ihāmutropādhi-nairāsyenāmuṣmin manaḥ-kalpanam etad eva naiṣkarmyam. “Devotional service is the process of worshiping the Supreme Lord. It consists of fixing the mind upon Him by becoming disinterested in all material designations, both in this life and the next. It results in the dissolution of all karma.” While it is certainly true that those who practice devotional service remain in material bodies and apparently material situations for some time, this is simply an expression of the inconceivable mercy of the Lord, who bestows the fruits of devotion only when it has become pure. In every stage of devotion, however, the Lord watches over His devotee and sees to the gradual elimination of his karma. Thus despite the fact that the happiness and distress devotees experience resemble ordinary karmic reactions, they are in fact given by the Lord Himself. As the Bhāgavatam (10.87.40) states, bhavad-uttha-śubhāśubhayoḥ: A mature devotee recognizes the superficially good and bad conditions he encounters as signs of the direct guidance of his ever well-wishing Lord.
But if the Lord is so compassionate to His devotees, why does He expose them to special suffering? This is answered by an analogy: A very affectionate father takes the responsibility of restricting his children’s play and making them go to school. He knows that this is a genuine expression of his love for them, even if the children fail to understand. Similarly, the Supreme Lord Viṣṇu is mercifully strict with all His dependents, not only with immature devotees struggling to become qualified. Even perfect saints like Prahlāda, Dhruva and Yudhiṣṭhira were subjected to great tribulations, all for their glorification.”
Source:A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Tenth Canto, Chapter 88 – Text 08