Knowledge of the intrinsic nature of the holy name is given in Bhakti-rasāmṛta-sindhu (1.2.233, quoted from the Padma Purāṇa):
nāma cintāmaṇiḥ kṛṣṇaś
pūrṇaḥ śuddho nitya-mukto
The holy name is a transcendental wish-fulfilling gem (cintāmaṇi), for there is no difference between Kṛṣṇa’s name (nāma) and Kṛṣṇa Himself (nāmī). In other words the holy name is the bestower of the supreme goal (parama-puruṣārtha). This name is the very form of transcendental mellows (caitanya-rasa-svarūpa). It is completely pure; that is, it is unlimited and eternally liberated, devoid of any connection with māyā.
harināma cintāmaṇi cid-rasa-svarūpa
pūrṇa jaḍātīta nitya kṛṣṇa-nija-rūpa
Nāma and nāmī are qualitatively non-different in principle. Therefore in the name “Kṛṣṇa” all the transcendental qualities of the possessor of the name are present. The holy name is always the complete Absolute Truth, unaffected by material matter. He is eternally liberated because He is never bound by the illusory energy. The holy name is Kṛṣṇa Himself and therefore the personification of the aggregate wealth of transcendental mellows. The holy name is a wish-fulfilling gem, able to give whatever one desires. Śrī-nāma-saṅkīrtana, which is the practice (sādhana), is non-different in every respect from Śrī Kṛṣṇa, who is the goal (sādhya). The one Absolute Truth, who is imbued with transcendental mellows consisting of eternity, knowledge and bliss (sac-cid-ānanda), is eternally present in these two manifested forms, nāma and nāmī.
Bhakti-rasāmṛta-sindhu (1.2.234) states:
na bhaved grāhyam indriyaiḥ
sevonmukhe hi jihvādau
svayam eva sphuraty adaḥ
The material senses, such as the tongue, cannot perceive Śrī Kṛṣṇa’s name, which appears automatically only on the transcendental senses of one in whose heart the desire to serve Kṛṣṇa has arisen.
nāma, rūpa, guṇa, līlā indriya-grāhya naya
sevā-mukhe kṛpā kari’ indriya udaya
It is a natural tendency of one who has the desire to serve Kṛṣṇa (sevonmukha) to be engaged in chanting Bhagavān’s holy name, which is His intrinsic form. The holy name Himself appears and begins to dance on the tongue and other senses of one who has a tendency towards śrī-nāma-sevā, in other words, an inclination for chanting. Bhagavān’s name can appear even on the tongues of animals. Examples of this are Bharata Mahārāja when he was leaving his deer body, and the elephant Gajendra when he was being pulled into the water by the crocodile.
Śrīmad-Bhāgavatam (11.21.2) states:
sve sve ’dhikāre yā niṣṭhā
sa guṇaḥ parikīrtitaḥ
viparyayas tu doṣaḥ syād
ubhayor eṣa nirṇayaḥ
To have unyielding steadiness on the path of dharma, according to one’s own qualification, is a virtue; conversely, to make endeavours that do not accord with one’s qualification is a fault.
adhikāra susammata kārye haya guṇa
viparīta kārye doṣa bujhibe nipuṇa
The purport of this verse is that virtue and fault are determined according to one’s qualification, and not by any other criteria.
Qualification for chanting the holy name is given in Śrīmad-Bhāgavatam (11.20.27–8):
veda duḥkhātmakān kāmān
parityāge ’py anīśvaraḥ
tato bhajeta māṁ prītaḥ
juṣamāṇaś ca tān kāmān
duḥkhodarkāṁś ca garhayan
If a person whose faith in hearing narrations of Me has been awakened is unable to give up sense enjoyment and the desire for it, even though he knows it gives misery, he should with a sincere heart condemn his inability to give it up. All the while, he should continue worshipping Me with firm faith, conviction and love.
kṛṣṇa-kathā śraddhā-lābha tyaje karmāsakti
duḥkhātmaka kāma-tyāge tabu nahe śakti
kāma-sevā kare tāhā kariyā garhaṇa
sudṛḍha-bhajane kāme kare vidhvaṁsana
puṇyamaya kāma-mātra uddiṣṭa ethāya
pāpa-kāme śraddhadhānera ādara nā haya
By the influence of association with devotees (sat-saṅga), a person develops a taste for hearing hari-kathā. At that time he will have no interest in any other activity, and with firm faith he will chant the name of Bhagavān continually. However, if due to his previous habits someone is unable to give up sense enjoyment or the desire for it, in his heart he condemns his inability to give it up.
Here, in these two verses, the intrinsic nature of bhakti is described by mentioning the first symptoms of the qualification for bhakti. Sarva-karmasu means sadness that comes as a result of performing all material Vedic activities and from their results; in other words, being distressed by a miserable mind. Kāmān means realising the miseries that result from the desires arising from associating with the opposite sex. If a person is unable to give up these desires, he should, from the beginning, have the following firm conviction: “If my attachment to household life is destroyed or if it increases, if my bhajana is full of millions of obstacles or if I go to hell because of offences, I will accept it all; but I will never give up devotion, even if Brahmā himself tells me to.” A person who performs bhajana with such firm conviction will certainly be successful. Even if desires causing misery arise from association with wife, children and so forth, a person should condemn the desires and continue fulfilling his worldly responsibilities. However, he should never give up bhakti. The desire for enjoyment will gradually diminish by hearing, chanting and so on, and one will ultimately attain bhakti.
The six vows favourable for bhakti are described in the third verse of Upadeśāmṛta:
utsāhān niścayād dhairyāt
saṅga-tyāgāt sato vṛtteḥ
ṣaḍbhir bhaktiḥ prasidhyati
Perfection in bhakti can be achieved by the following six kinds of practices: (1) to be enthusiastic in following the rules which nourish devotion; (2) to have firm faith in the statements of the scriptures and in śrī gurudeva, whose words are fully in line with the scriptures; (3) to be patient in the practice of bhakti, even in the midst of obstacles or when there is a delay in attaining one’s desired success; (4) to follow the limbs of bhakti, such as śravaṇa and kīrtana, and to give up one’s material sense enjoyment for the pleasure of Kṛṣṇa; (5) to give up association that is opposed to bhakti, like illicit connection with women, the association of those who are overly attached to women and the association of māyāvādīs, atheists and pseudo-religionists; and (6) to adopt the good behaviour and character of devotees.
utsāha, dṛḍhatā, dhairya bhakti kārye rati
saṅga-tyāga, sādhu-vṛtti chaye kara mati
To maintain one’s existence and to cultivate bhakti are both necessary for devotees. The first half of this verse indicates the activities that nourish bhakti and the second half describes how a devotee should conduct his life. Enthusiasm (utsāha), conviction (niścaya), patience (dhairya), executing activities that nourish devotion (tat-tat-karma-pravartana), renouncing bad association (saṅga-tyāga) and adopting the good behaviour and character of pure devotees (sad-vṛtti) are the means to attain perfection in bhakti.
Utsāha means to remain indifferent in every respect to the practices related to jñāna, karma and anyābhilāṣa (desires other than to serve Kṛṣṇa), and also to one’s preferred variety of material enjoyment, while steadily executing the limbs of sādhana-bhakti. “Bhagavad-bhakti is the only ultimate objective for all living entities” – such firm faith is called niścaya, conviction. Straying to the paths of karma, jñāna and so forth makes one’s mind restless, and following their practices only produces suffering in the end. Therefore the firm resolve that the path of bhakti is the only constitutional path for sincere living entities is called dhairya, fortitude.
Śrī Haridāsa Ṭhākura took a vow never to give up chanting and he strictly adhered to it:
khaṇḍa-khaṇḍa hai deha yāya yadi prāṇa
tabu āmi vadane nā chāḍi harināma
Śrī Caitanya-bhāgavata (Ādi-khaṇḍa 16.94)
Even if my body is cut to pieces and my life air exits, I will never abandon the chanting of harināma.
This is the ideal in the realm of bhakti.
To cultivate the practices of bhakti such as hearing hari-kathā, performing kīrtana of Bhagavān’s name, and meditating on Bhagavān’s name, form and pastimes with firm conviction like Haridāsa Ṭhākura, is tat-tat-karma-pravartana.
Only the association of Bhagavān’s devotees is desirable. One should never associate with karmīs, jñānīs or those filled with desires other than to serve Kṛṣṇa. One should know such people to be less intelligent and indulgent. Karma, jñāna, aṣṭāṅga-yoga and so forth, which are devoid of the desire to please Bhagavān, are not steps on the path of bhakti. The path of bhakti is characterised by saintly conduct (sādhu-vṛtti), because all virtuous qualities certainly reside within a person who possesses devotion.
Enthusiasm for serving Kṛṣṇa, conviction in service, being steadfast in kṛṣṇa-sevā, ensuring that all endeavours are solely for service to Kṛṣṇa, renouncing the company of all others except Kṛṣṇa’s devotees and following in the footsteps of Kṛṣṇa’s devotees are the six practices that enhance bhakti.