A self-surrendered devotee of the Lord is called nārāyaṇa-parāyaṇa. Such a person is never afraid of any place or person, not even of death. For him nothing is as important as the Supreme Lord, and thus he gives equal importance to heaven and hell. He knows well that both heaven and hell are creations of the Lord, and similarly life and death are different conditions of existence created by the Lord. But in all conditions and in all circumstances, remembrance of Nārāyaṇa is essential. The nārāyaṇa-parāyaṇa practices this constantly. Mahārāja Parīkṣit was such a pure devotee.
(Srimad Bhagavatam----1:18:2----purport).

"If even for a moment remembrance of Vāsudeva, the Supreme Personality of Godhead, is missed, that is the greatest loss, that is the greatest illusion, and that is the greatest anomaly." The Lord can be worshiped in all stages of life. For instance, even in the wombs of their mothers Mahārāja Prahlāda and Mahārāja Parīkṣit worshiped the Lord; even in his very childhood, at the age of only five years, Dhruva Mahārāja worshiped the Lord; even in full youth, Mahārāja Ambarīṣa worshiped the Lord; and even at the last stage of his frustration and old age Mahārāja Dhṛtarāṣṭra worshiped the Lord. Ajāmila worshiped the Lord even at the point of death, and Citraketu worshiped the Lord even in heaven and in hell.
(Srimad Bhagavatam----2:9:36----purport).

Those who are devotees of the Lord are not afraid of any condition of life, provided there is constant engagement in the service of the Lord. It is said of the nārāyaṇa-para, or those who are devotees of Nārāyaṇa, the Supreme Personality of Godhead, na kutaścana bibhyati (S.B.6:17:28). They are not afraid of entering a hellish condition, for since they are engaged in the transcendental loving service of the Lord, heaven or hell is the same for them. In material life both heaven and hell are one and the same because they are material; in either place there is no engagement in the Lord's service. Therefore those who are engaged in the service of the Lord see no distinction between heaven and hell; it is only the materialists who prefer one to the other.
(Srimad Bhagavatam----3:15:49----purport).

Under the influence of māyā, the living entity becomes exactly like a person haunted by a ghost. Such a person speaks all kinds of nonsense. When the living entity is covered by the influence of māyā, he becomes a so-called scientist, philosopher, politician or socialist, and at every moment presents different plans for the benefit of human society. All these plans are ultimately failures because they are illusory. In this way the living entity forgets his position as an eternal servant of the Lord. He instead becomes a servant of māyā. In any case he remains a servant. It is his misfortune that by forgetting his real contact with the Supreme Lord, he becomes a servant of māyā. As servant of māyā, he sometimes becomes a king, sometimes an ordinary citizen, sometimes a brāhmaṇa, a śūdra, and so on. Sometimes he is a happy man, sometimes a prosperous man, sometimes a small insect. Sometimes he is in heaven and sometimes in hell. Sometimes he is a demigod, and sometimes he is a demon. Sometimes he is a servant, and sometimes he is a master. In this way the living entity wanders all over the universe. Only when he comes in contact with the bona fide spiritual master can he understand his real constitutional position. He then becomes disgusted with material existence. At that time, in full Kṛṣṇa consciousness, he regrets his past experiences in material existence. This regret is very beneficial because it purifies the living entity of material, conditional life. He then prays to the Lord to engage in His service, and at that time, Kṛṣṇa grants liberation from the clutches of māyā.
(Srimad Bhagavatam----4:29:29----purport).

Devotees like the great sage Nārada, who travel all over to preach, are called goṣṭhānandī. Nārada Muni is always wandering throughout the universe just to create different types of devotees. Nārada even made a hunter a devotee. He also made Dhruva Mahārāja and Prahlāda devotees. Actually, all devotees are indebted to the great sage Nārada, for he has wandered both in heaven and in hell. A devotee of the Lord is not even afraid of hell. He goes to preach the glories of the Lord everywhere—even in hell—because there is no distinction between heaven and hell for a devotee.
(Srimad Bhagavatam----4:30:37----purport).

The word kṛṣṇa-rpita-prāṇaḥ refers to a devotee who dedicates his life to serving Kṛṣṇa, not to being saved from the path to hellish life. A devotee is nārāyaṇa-parāyaṇa, or vāsudeva-parāyaṇa, which means that the path of Vāsudeva, or the devotional path, is his life and soul. Nārāyaṇa-parāḥ sarve na kutaścana bibhyati (S.B.6:17:28): such a devotee is not afraid of going anywhere. There is a path toward liberation in the higher planetary systems and a path toward the hellish planets, but a nārāyaṇa-para devotee is unafraid wherever he is sent; he simply wants to remember Kṛṣṇa, wherever he may be. Such a devotee is unconcerned with hell and heaven; he is simply attached to rendering service to Kṛṣṇa. When a devotee is put into hellish conditions, he accepts them as Kṛṣṇa's mercy: tat te 'nukampāṁ susamīkṣamāṇaḥ (S.B.10:14:8). He does not protest, "Oh, I am such a great devotee of Kṛṣṇa. Why have I been put into this misery?" Instead he thinks, "This is Kṛṣṇa's mercy." Such an attitude is possible for a devotee who engages in the service of Kṛṣṇa's representative. This is the secret of success.
(Srimad Bhagavatam----6:1:16----purport).

One who desires nothing but Kṛṣṇa and who is not influenced by the process of jñāna-mārga (cultivation of knowledge) actually becomes free from ignorance. A first-class person is one who is not influenced by karma (fruitive activity) or yoga (mystic power). He simply depends on Kṛṣṇa and is satisfied in his devotional service. According to Śrīmad-Bhāgavatam (6.17.28): nārāyaṇa-parāḥ sarve na kutaścana bibhyati. Such a person is never afraid of anything. For him, heaven and hell are the same.
(Sri Caitanya Caritamrta-----2:19:150----purport).

The higher planetary systems in this material world are Bhūrloka, Bhuvarloka, Svargaloka, Maharloka, Janaloka, Tapoloka, and up to Satyaloka, or Brahmaloka. Whichever of these planets one rises to in his next life, one must finally return to earth. What to speak of the next life, even in this life the high position one attains after considerable hard work—such as king, emperor, minister, governor, or president—is lost after some time, and one is thrown back to a mean and humble status. Only leaders who have experienced this kind of humiliation can know the trepidation that accompanies it. But if at any stage of life the grossly foolish miscreants described in the Gītā decide to render devotional service to Lord Kṛṣṇa, they can escape the ferris wheel of karma. On this wheel, sometimes one goes to heaven and sometimes to hell, sometimes one is born a king and sometimes a slave, sometimes one becomes a brāhmaṇa and sometimes śūdra, and so it goes on. But once a person enters the spiritual abode of the Supreme Lord, he begins his eternal life in his original, constitutional position.
(Renunciation Through Wisdom).

As stated before, a pure devotee of the Lord has nothing to do with mundane religiosity, economic development, sense gratification, or salvation, nor is he concerned whether his standard of material existence is the highest or the lowest. To him, heaven and hell are of equal value. He is not afraid of going to hell for the service of the Lord, nor is he glad to live in heaven without the service of the Lord. In any circumstance his consciousness is fixed on the Lord's lotus feet, whose beauty defies the most beautiful lotus flower of the mundane world.
(Mukunda-Mala-Stotra).

The inhabitants of Vṛndāvana said, “By the will of the supreme authority and according to the results of our own work, we may take our birth anywhere. It doesn’t matter where we are born, but our only prayer is that we may simply be engaged in Kṛṣṇa consciousness.” A pure devotee of Lord Kṛṣṇa never desires to be promoted to the heavenly planets, or even to Vaikuṇṭha or Goloka Vṛndāvana, because he has no desire for his own personal satisfaction. A pure devotee regards heaven and hell to be on an equal level. Without Kṛṣṇa, heaven is hell; and with Kṛṣṇa, hell is heaven.
(Krsna Book).