Śrī Gurudeva should recite the sixteen word hare kṛṣṇa mantra to the disciple before initiating him into the gopāla-mantra, which brings auspiciousness to the three worlds. To receive this gopāla-mantra, the disciple must sit facing north and receive the mantra in his right ear.

In śāstras such as the Brahma Yāmala, Lord Śiva describes the svarūpa (form) of the mahāmantra:

hariṁ vinā nāsti kiñcat pāpa-nistārakaṁ kalau

tasmāl lokoddhāraṇārthaṁ hari-nāma prakāśayet

sarvatra mucyate loko mahā-pāpāt kalau yuge

hare-kṛṣṇa-pada-dvandvaṁ kṛṣṇeti ca pada-dvayam

tathā hare-pada-dvandvaṁ hare-rāma iti dvayam

tad-ante ca mahā-devi rāma rāma dvayaṁ vadet

hare hare tato brūyād hari-nāma samuccararet

mahā-mantraṁ ca kṛṣṇasya sarva-pāpa-praṇāśakam iti

Hey Mahādevī! Look! In Kali-yuga there is no easier way to eradicate sins other than śrī harināma. It is therefore essential to propagate śrī harināma among the general populace. The people in Kali-yuga can be easily liberated from the greatest hell by performing saṅkīrtana of this mahāmantra. To chant the mahāmantra, first chant hare kṛṣṇa twice, then chant kṛṣṇa twice, then hare twice. After that, chant hare rāma twice, then rāma twice and again hare twice. One should chant, articulate and perform sankīrtana etc., of Śrī Kṛṣṇa’s mahāmantra, which destroys all sins.  This is described in these two stanzas.

The Rādhā Tantra states:

śṛṇu mātar mahā-māye viśva-bīja-svarūpiṇi

hari-nāmno mahāmāye kramaṇavat sureśvari

A bhakta prays, “He viśva-bīja-svarūpiṇi (seed of the universe)! Sureśvari (who are worshipable by the demigods)! Mahāmāyā! Mātā! Please hear my prayer and explain to me the sequence of the mahāmantra.”

In response to this, Devī says:

hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare

hare rāma hare rāma rāma rāma hare hare

dvātriṁśad akṣarāṇy eva kalau nāmāni sarvadam

etan mantraṁ putra-śreṣṭha prathamaṁ śṛṇuyān naraḥ

O best among sons! The mahāmantra for Kali-yuga bestows all perfection. This mahāmantra, Śrī Kṛṣṇa nāma, is composed of sixteen names and thirty-two syllables: hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare / hare rāma hare rāma rāma rāma hare hare. Therefore, a person who desires his own welfare should first hear this mahāmantra from his Gurudeva.

In the same Rādhā-Tantra, Tripurā-devī also suggests:

hari-nāmnā vinā putra dīkṣā ca viphalā bhavet

guru-deva-mukhāc chrutvā harināma parākṣaram

brāhmaṇa-kṣatra-viṭ-śūdrāḥ śrutvā nāma parākṣaram

dīkṣāṁ kuryuḥ suta-śreṣṭha mahā-vidyā-su-sundara

O best among sons, you are conversant with the greatest jñāna. Look! If you hear the gopāla-mantra from Śrī Gurudeva before hearing the hare kṛṣṇa mahāmantra, the results of the gopāla-mantra will become void. Therefore, persons of all varṇas, such as brāhmaṇas and kṣatriyas, first have to hear this mahāmantra from Śrī Gurudeva before they accept initiation into the gopāla-mantra.

The Padma-Purāṇa also states:

dvātriṁśad akṣaraṁ mantraṁ nāma ṣoḍaśakānvitam

prajapan vaiṣṇavo nityaṁ rādhā-kṛṣṇa-sthalaṁ labhet

Any Vaiṣṇava who constantly chants the hare kṛṣṇa mahāmantra, which is endowed with sixteen names consisting of thirty-two syllables, will certainly attain the abode of Śrī Śrī Rādhā Kṛṣṇa in Goloka Vrṇdāvana Dhāma.

In the Rādhā-hṛdaya-khaṇḍa of the Brahmāṇḍa-Purāṇa, Romaharṣaṇa Sūta prays to Śrī Veda Vyāsa as follows:

yat tvayā kīrtitaṁ nātha hari-nāmeti saṁjñitam

mantraṁ brahma-padaṁ siddhi karaṁ tad vada no vibho

He Vibho! He Prabhu! Please instruct me in the brahma-svarūpa nāma-mantra of Śrī Hari which is the bestower of all perfections.

In reply, Śrī Veda Vyāsa gives the following instruction:

grahaṇād yasya mantrasya dehī brahma-mayo bhavet

sadyaḥ pūtaḥ surā-po ‘pi sarva-siddhi-yuto bhavet

tad ahaṁ te ‘bhidhāsyāmi mahā-bhāgavato hy asi

hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare

hare rāma hare rāma rāma rāma hare hare

iti ṣoḍaśakaṁ nāmnāṁ tri-kāla-kalmaṣāpaham

nātaḥ parataropāyaḥ sarva-vedeṣu vidyate

O my son, I will certainly instruct you in that mahāmantra, the acceptance of which a person in the bodily conception of life can be liberated and even a drunkard can quickly become purified and attain all perfection. I will instruct you because you are a mahā-bhāgavata and a suitable candidate. Just see! The sixteen word mahāmantra, hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare / hare rāma hare rāma rāma rāma hare hare, can destroy the sins of the three worlds. The four Vedas do not mention a method for achieving liberation from material bondage superior to the chanting of this mahāmantra.

Ananta-Saṁhitā also states:

hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare

hare rāma hare rāma rāma rāma hare hare

ṣoḍasaitāni nāmāni dvā-triṁśad varṇakāṇi hi

kalāu yuge mahāmantraḥ sammato jīva-tāraṇe

utsṛjyaitān mahāmantraṁ ye tv anyat kalpitaṁ padam

mahā-nāmeti gāyanti te śāstra-guru-laṅghinaḥ

All śāstras agree that the hare kṛṣṇa mahāmantra, which is composed of sixteen names and thirty-two syllables, is the supreme mantra for delivering the jīvas in Kali-yuga. Those who neglect this mahāmantra and accept any other process, due to their own imagination or the imagination of others, disobey guru and śāstra. If someone asks, ‘Why is this sixteen word hare kṛṣṇa mantra the mahāmantra?’ then the following answer is given. ‘Among all of Kṛṣṇa’s names‚ no name other than Hari can easily take away sins, great misfortune and ignorance. No name other than Kṛṣṇa can deliver prema. And no name other than Rāma can bestow liberation.’ This is why the mahāmantra is composed of these three primary names. Secondly, these sixteen names are an invocation. Thus oṁ, namaḥ, klīṁ, svāhā, etc., are not required to make the mantra more potent. For this reason it is called the mahāmantra.

The Sanat-Kumāra-Saṁhitā states:

hare kṛṣṇau dvir āvṛttau kṛṣṇa tādṛk tathā hare

hare rāma tathā rāma tathā tādṛk hare punaḥ

hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare

hare rāma hare rāma rāma rāma hare hare

This means first chant hare kṛṣṇa twice, then kṛṣṇa twice, followed by hare twice. Then chant hare rāma twice, rāma twice and then hare twice. By this we get the mahāmantra, hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare / hare rāma hare rāma rāma rāma hare hare.

In the Yajur-veda, the Kali-santaraṇa Upaniṣad also describes the svarūpa and glories of the mahāmantra in this way:

hariḥ oṁ. dvāparānte nārado brahmāṇaṁ jagāma kathaṁ bhagavan! gāṁ paryaṭan kalim santareyam iti. sa hovāca brahmā sādhu pṛṣto ‘smi sarva-śruti-rahasyaṁ gopyaṁ tac chṛṇu yena kali-saṁsāraṁ tariṣyasi. bhagavata ādi-puruṣasya nārāyaṇasya nāmoccāraṇa-mātreṇa nirdhūta-kalir bhavati. nāradaḥ punaḥ papraccha. tan-nāma kim iti? sa hovāca hiraṇya-garbhaḥ, “hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare / hare rāma hare rāma rāma rāma hare hare.” iti ṣoḍaśakaṁ nāmnāṁ kali-kalmaṣa-nāśanam. nātaḥ parataropāyaḥ sarva-vedeṣu dṛśyate. iti ṣoḍaśa-kalāvṛtasya jīvasyāvaraṇa-vināśanam. tataḥ prakāśate paraṁ brahma meghāpāye ravi-raśmi-maṇdalīveti. punar nāradaḥ papraccha. bhagavan ko ‘sya vidhir iti? sa hovāca nāsya vidhir iti. sarvadā śūcir aśucir vā paṭhan brahmaṇaḥ sa-lokatāṁ samīpatām sa-rūpa

tāṁ sāyujyatām iti.

“At the end of Dvārapa-yuga, Śrī Nārada went to Śrī Brahmā, and, after offering his obeisances inquired, ‘O Lord, how can I cross beyond the influence of this age of Kali while wandering on this earthly planet?’

“Brahmājī replied, ‘O son, you have asked an excellent question. Please hear the most confidential secret of the entire Vedas by which you can easily cross this world of Kali. By uttering the name of that ādi-puruṣa who is Bhagavān Śrī Nārāyaṇa (Kṛṣṇa), the personality of Kali-yuga begins to tremble.’

“Nāradajī further inquired, ‘Which name of Śrī Bhagavān and what is its svarūpa?’»

“In reply Brahmājī said, ‘Hare kṛṣṇa hare kṛṣṇa kṛṣṇa kṛṣṇa hare hare / hare rāma hare rāma rāma rāma hare hare. This mahāmantra, thus composed of sixteen names, can completely destroy all the sins of Kali-yuga. A superior sādhana does not appear in the entire Vedas. The mahāmantra is covered by sixteen qualities, which means that it can destroy the five gross elements (pañca-bhūta) and the eleven senses which cover the jīva. Then Paraṁbrahma manifests before the jīva, just like the sun whose rays shine brightly when the clouds’ covering is removed.’

“Nāradajī then asked, ‘Oh Lord, what are the rules and regulations for chanting this mahāmantra?’

“Brahmājī said, ‘There are no rules and regulations for chanting this mahāmantra. One can chant in a pure or an impure state. Moreover, by clearly pronouncing this mahāmantra, one can attain brahma (sālokya, samīpya, sarūpya and sāyujya). Not only that, one can attain kṛṣṇa-prema, the fifth goal of human life (pañcama-puruṣārtha).’”

Śrī Bhakti-Candrikā, 7th Paṭala states:

atha mantra-varaṁ vakṣye / dvātrimśad akṣarānvitam

sarva-pāpa-praśamanaṁ / sarva-durvāsanānalam

catur-varga-pradaṁ saumyaṁ / bhakti-daṁ prema-pūrvakam

durbuddhi-haraṇaṁ śuddha / sattva-buddhi-pradāyakam

sarvārādhyaṁ sarva-sevyaṁ / sarveṣāṁ kāma-pūrakam

sarvādhikāra-samyuktaṁ / sarva-lokaika-bāndhavam

sarvākarsaṇa-samyuktaṁ / duṣṭa-vyādhi-vināśanam

dīkṣā-vidhi-vihīnaṁ ca / kālākāla-vivarjitam

vāṇ-mātreṇārcitaṁ bāhya / pūjā-vidhy-anapekṣakam

jihvā-sparśana-mātreṇa / sarveṣāṁ phala-dāyakam

deśa-kālāniyamitaṁ / sarva-vādi-susammatam

“This mahāmantra is endowed with thirty-two syllables and can destroy all sins. Just as fire destroys, this mahāmantra can destroy all evil habits and bestow dharma, artha, kāma and mokṣa. Its beautiful form (svarūpa) is capable of stealing all of one’s foolish, ignorant mentality, and it is the giver of śuddha-sattvika intelligence. It bestows the symptoms of prema-bhakti. It is worshipable and is worthy of being served by all. Śrī nāma fulfills everyone’s desires. All are qualified to serve this mahāmantra, meaning all are qualified to perform saṅkīrtana of the mahāmantra. This mahāmantra is the personal well-wisher of everyone and is endowed with the potency to attract all. It is the destroyer of all afflictions. It does not consider the rules of dīkṣā, and is not restricted by time. The mahāmantra is worshipped just by saying it. No external paraphernalia is required. It is capable of giving results simply by its contact with the tongue, without considering the rules pertaining to time, place and circumstance.”

The Pippalāda branch of the Athārva-veda states:

sva-nāma-mūla-mantreṇa

     sarvahlādayati vibhuḥ

sa eva mūla-mantraṁ japati

     harir iti kṛṣṇa iti rāma iti

“That mahāmantra, which is composed of the name, form, etc., of Śrī Kṛṣṇa, the origin of all avatāras‚ is making everyone joyful. He Himself, in the form of Śrī Kṛṣṇa Caitanya Mahāprabhu, is clearly chanting the hare kṛṣṇa mahāmantra, the source of all mantras.”

The following śloka explains the result of performing kīrtana etc. of the mahāmantra:

mantro guhyaḥ paramo bhakti-vedyaḥ

nāmāny aṣṭāv aṣṭa ca śobhanāni

tāni nityaṁ ye japanti dhīrās

te vai māyām atitaranti nānye

paramaṁ mantraṁ parama-

rahasyaṁ nityam āvartayati

“The mahāmantra is most confidential and can only be understood through bhakti. Eight of its sixteen charming words are hare kṛṣṇa and the other eight are hare rāma. Therefore, only those intelligent persons who constantly chant these names will be liberated from māyā—and not others. That is why intelligent persons always chant, perform kīrtana ofand remember the mahāmantra.”

In the Brahmāṇḍa Purāṇa (Northern Division, Chapter 6)
Pippalāda mentions that Vṛṣabhānu Mahārāja once prayed to Kratu Muni, “O Lord, if you want to favor me, then please donate to me the names of Hari.” At that moment the saintly Kratu Muni gave him the sixteen name mahāmantra. Therefore, an intelligent person should constantly perform saṅkīrtana of this mahāmantra: ma-saṅkīrtanaṁ tasmāt sadā kāryaṁ vipaścitā.

Srila Gurudeva ki Jaya! (Excerpted from the Bhaktabandhav book publication, “Srī Harināma Mahāmantra” . Available from: rasik@kripa.tv )