"Kṛṣṇa says, 'If one engages in My transcendental loving service but at the same time wants the opulence of material enjoyment, he is very, very foolish. Indeed, he is just like a person who gives up ambrosia to drink poison. Since I am very intelligent, why should I give this fool material prosperity? Instead I shall induce him to take the nectar of the shelter of My lotus feet and make him forget illusory material enjoyment.' " If a devotee maintains some material desire and at the same time very sincerely desires to engage at the lotus feet of Kṛṣṇa, Kṛṣṇa may directly give him unalloyed devotional service and take away all his material desires and possessions. This is the Lord's special favor to devotees. Otherwise, if one takes to Kṛṣṇa's devotional service but still has material desires to fulfill, he may become free from all material desires, as Dhruva Mahārāja did, but this may take some time. However, if a very sincere devotee wants only Kṛṣṇa's lotus feet, Kṛṣṇa directly gives him the position of śuddha-bhakti, unalloyed devotional service.
(Srimad Bhagavatam----8:16:21----purport).

"One should render transcendental loving service to the Supreme Lord Kṛṣṇa favorably and without desire for material profit or gain through fruitive activities or philosophical speculation. That is called pure devotional service." One simply has to concentrate upon the lotus feet of Vāsudeva, Kṛṣṇa (sa vai manaḥ kṛṣṇa-padāravindayoḥ (S.B.9:4:18). Then the mind and senses will be controlled, and one can engage himself fully in the devotional service of the Lord. The devotee does not need to practice the haṭha-yoga system to control the mind and senses; his mind and senses are automatically controlled because of unalloyed devotional service to the Lord.
(Srimad Bhagavatam----8:17:2-3----purport).

"One who engages in the spiritual activities of unalloyed devotional service immediately transcends the modes of material nature and is elevated to the spiritual platform." From the very beginning of one's transactions in bhakti, one is situated on the transcendental platform. Vasudeva and Devakī, therefore, being situated in a completely pure devotional state, are beyond this material world and are not subject to material fear. In the transcendental world, however, because of pure devotion, there is a similar conception of fear, which is due to intense love.
(Srimad Bhagavatam----10:3:31----purport).

By His one plenary portion as Paramātmā, the Lord controls innumerable universes, with all their demigods; yet He agrees to be controlled by a devotee. In the Upaniṣads it is said that the Supreme Personality of Godhead can run with more speed than the mind, but here we see that although Kṛṣṇa wanted to avoid being arrested by His mother, He was finally defeated, and mother Yaśodā captured Him. Lakṣmī-sahasra-śata-sambhrama-sevyamānam: (Bs. 5.29) Kṛṣṇa is served by hundreds and thousands of goddesses of fortune. Nonetheless, He steals butter like one who is poverty-stricken. Yamarāja, the controller of all living entities, fears the order of Kṛṣṇa, yet Kṛṣṇa is afraid of His mother's stick. These contradictions cannot be understood by one who is not a devotee, but a devotee can understand how powerful is unalloyed devotional service to Kṛṣṇa; it is so powerful that Kṛṣṇa can be controlled by an unalloyed devotee. This bhṛtya-vaśyatā does not mean that He is under the control of the servant; rather, He is under the control of the servant's pure love. In Bhagavad-gītā (1.21) it is said that Kṛṣṇa became the chariot driver of Arjuna.
(Srimad Bhagavatam----10:9:19----purport).

Fear arises when a living entity misidentifies himself as the material body because of absorption in the external, illusory energy of the Lord. When the living entity thus turns away from the Supreme Lord, he also forgets his own constitutional position as a servant of the Lord. This bewildering, fearful condition is effected by the potency for illusion, called māyā. Therefore, an intelligent person should engage unflinchingly in the unalloyed devotional service of the Lord, under the guidance of a bona fide spiritual master, whom he should accept as his worshipable deity and as his very life and soul.
(Srimad Bhagavatam----11:2:37----translation).

With steady intelligence you should develop unalloyed devotional service by careful worship of the spiritual master, and with the sharpened ax of transcendental knowledge you should cut off the subtle material covering of the soul. Upon realizing the Supreme Personality of Godhead, you should then give up that ax of analytic knowledge.
(Srimad Bhagavatam----11:12:24----translation).

Only by practicing unalloyed devotional service with full faith in Me can one obtain Me, the Supreme Personality of Godhead. I am naturally dear to My devotees, who take Me as the only goal of their loving service. By engaging in such pure devotional service, even the dog-eaters can purify themselves from the contamination of their low birth.
(Srimad Bhagavatam----11:14:21----translation).