A sincere devotee of the Lord shuns all material sense enjoyment due to his higher taste for spiritual enjoyment in the association of the Lord
(Bhagavad-Gita----2:62----purport).

The sincere devotee engaged in Kṛṣṇa consciousness cannot be without knowledge
(Bhagavad-Gita----8:10----purport).

A sincere devotee must, therefore, be prepared to hear the Vedic literature like the Upaniṣads, Vedānta and other literatures left by the previous authorities or Gosvāmīs
(Srimad Bhagavatam----1:2:12----purport).

The sincere devotee should go on with sincere service of the Lord. The Lord will give proper direction as to how and where it has to be done
(Srimad Bhagavatam----1:6:22----purport).

The life of a sincere devotee of the Lord is thus explained in a nutshell by Nārada Muni by his personal example. Such a devotee, after his initiation by the Lord or His bona fide representative, takes very seriously chanting of the glories of the Lord and traveling all over the world so that others may also hear the glories of the Lord. Such devotees have no desire for material gain. They are conducted by one single desire: to go back to Godhead. This awaits them in due course on quitting the material body. Because they have the highest aim of life, going back to Godhead, they are never envious of anyone, nor are they proud of being eligible to go back to Godhead. Their only business is to chant and remember the holy name, fame and pastimes of the Lord and, according to personal capacity, to distribute the message for others' welfare without motive of material gain.
(Srimad Bhagavatam----1:6:26----purport).

Revival of the dormant affection or love of Godhead does not depend on the mechanical system of hearing and chanting, but it solely and wholly depends on the causeless mercy of the Lord. When the Lord is fully satisfied with the sincere efforts of the devotee, He may endow him with His loving transcendental service. But even with the prescribed forms of hearing and chanting, there is at once mitigation of the superfluous and unwanted miseries of material existence. Such mitigation of material affection does not wait for development of transcendental knowledge. Rather, knowledge is dependent on devotional service for the ultimate realization of the Supreme Truth.
(Srimad Bhagavatam----1:7:6----purport).

The devotee does not have to learn anything new from the Lord because the Lord teaches the sincere devotee always from within
(Srimad Bhagavatam----1:9:17----purport).

One may live in the darkest jungle alone out of home, but a steadfast devotee knows very well that he is not alone. The Supreme Personality of Godhead is with him, and He can protect His sincere devotee in any awkward circumstance
(Srimad Bhagavatam----1:13:27----purport).

The sincere devotee is thus assured by the Lord of going back to Godhead
(Srimad Bhagavatam----1:19:36----purport).

In the Brahma-saṁhitā it is said that the Lord is never to be found by becoming a great scholar of the Vedic literatures, but He is very easily approachable through His pure devotee. In Vṛndāvana all the pure devotees pray for the mercy of Śrīmatī Rādhārāṇī, the pleasure potency of Lord Kṛṣṇa. Śrīmatī Rādhārāṇī is a tenderhearted feminine counterpart of the supreme whole, resembling the perfectional stage of the worldly feminine nature. Therefore, the mercy of Rādhārāṇī is available very readily to the sincere devotees, and once She recommends such a devotee to Lord Kṛṣṇa, the Lord at once accepts the devotee's admittance into His association. The conclusion is, therefore, that one should be more serious about seeking the mercy of the devotee than that of the Lord directly, and by one's doing so (by the good will of the devotee) the natural attraction for the service of the Lord will be revived.
(Srimad Bhagavatam----2:3:23----purport).

This humbleness of the pure devotee, who is one hundred percent engaged in His service, puts the devotee of the Lord in a trance by which to realize everything, because to the sincere devotee of the Lord, the Lord reveals Himself.
(Srimad Bhagavatam----2:4:21----purport).

When a sincere devotee reads Bhagavad-gītā, this is as good as seeing the Lord face to face in his personal presence, but this is not so for the mundane wrangler.
(Srimad Bhagavatam----3:5:13----purport).

The Lord is transcendental to our sense experience, but He reveals Himself to the sincere devotee.
(Srimad Bhagavatam----3:5:18----purport).

The Supreme Personality of Godhead in His Paramātmā feature is situated in everyone's heart. He knows, therefore, the past, present and future of every individual person as well as his desires, activities and everything about him. It is stated in Bhagavad-gītā that He is seated in the heart as a witness. The Personality of Godhead knew the heart's desire of Kardama Muni, and He had already arranged for the fulfillment of his desires. He never disappoints a sincere devotee, regardless of what he wants, but He never allows anything which will be detrimental to the individual's devotional service.
(Srimad Bhagavatam----3:21:23----purport).

The sincere devotee who associates with devotees gets the opportunity to hear and contemplate this subject of the pastimes of the Lord, and the result is that he feels distaste for so-called happiness in this or that world, in heaven or on other planets.
(Srimad Bhagavatam----3:25:26----purport).

Anyone who is a sincere devotee of Lord Kṛṣṇa and who preaches this cult, speaking only on the basis of Kṛṣṇa's instructions, is understood to be virajam, or free from the defects of material contamination.
(Srimad Bhagavatam----4:21:42----purport).

If a sincere devotee renders service to the Lord or to the arcā-vigraha, the form of the Lord, all his activities prove successful because the Lord is present within his heart and understands his sincerity.
(Srimad Bhagavatam----4:30:29----purport).

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).