CC Ādi 7.72

mūrkha tumi, tomāra nāhika vedāntādhikāra
‘kṛṣṇa-mantra’ japa sadā, — ei mantra-sāra
Word for word: 
mūrkha tumi — You are a fool; tomāra — Your; nāhika — there is not; vedānta — Vedānta philosophy; adhikāra — qualification to study; kṛṣṇa-mantra — the hymn of Kṛṣṇa (Hare Kṛṣṇa); japa — chant; sadā — always; ei — this; mantra — hymn; sāra — essence of all Vedic knowledge.
Translation: 
“ ‘You are a fool,’ he said. ‘You are not qualified to study Vedānta philosophy, and therefore You must always chant the holy name of Kṛṣṇa. This is the essence of all mantras, or Vedic hymns.
Purport: 

Śrī Bhaktisiddhānta Sarasvatī Gosvāmī Mahārāja comments in this connection, “One can become perfectly successful in the mission of his life if he acts exactly according to the words he hears from the mouth of his spiritual master.” This acceptance of the words of the spiritual master is called śrauta-vākya, which indicates that the disciple must carry out the spiritual master’s instructions without deviation. Śrīla Viśvanātha Cakravartī Ṭhākura remarks in this connection that a disciple must accept the words of his spiritual master as his life and soul. Śrī Caitanya Mahāprabhu here confirms this by saying that since His spiritual master ordered Him only to chant the holy name of Kṛṣṇa, He always chanted the Hare Kṛṣṇa mahā-mantra according to this direction (‘kṛṣṇa-mantra’ japa sadā, — ei mantra-sāra).

Kṛṣṇa is the origin of everything. Therefore when a person is fully Kṛṣṇa conscious it is to be understood that his relationship with Kṛṣṇa has been fully confirmed. Lacking Kṛṣṇa consciousness, one is only partially related with Kṛṣṇa and is therefore not in his constitutional position. Although Śrī Caitanya Mahāprabhu is the Supreme Personality of Godhead Kṛṣṇa, the spiritual master of the entire universe, He nevertheless took the position of a disciple in order to teach by example how a devotee should strictly follow the orders of a spiritual master in executing the duty of always chanting the Hare Kṛṣṇa mahā-mantra. One who is very much attracted to the study of Vedānta philosophy must take lessons from Śrī Caitanya Mahāprabhu. In this age, no one is actually competent to study Vedānta, and therefore it is better that one chant the holy name of the Lord, which is the essence of all Vedic knowledge, as Kṛṣṇa Himself confirms in the Bhagavad-gītā (15.15):

vedaiś ca sarvair aham eva vedyo
vedānta-kṛd veda-vid eva cāham

“By all the Vedas, I am to be known. Indeed, I am the compiler of Vedānta, and I am the knower of the Vedas.

Only fools give up the service of the spiritual master and think themselves advanced in spiritual knowledge. In order to check such fools, Caitanya Mahāprabhu Himself presented the perfect example of how to be a disciple. A spiritual master knows very well how to engage each disciple in a particular duty, but if a disciple, thinking himself more advanced than his spiritual master, gives up his orders and acts independently, he checks his own spiritual progress. Every disciple must consider himself completely unaware of the science of Kṛṣṇa and must always be ready to carry out the orders of the spiritual master to become competent in Kṛṣṇa consciousness. A disciple should always remain a fool before his spiritual master. Therefore sometimes pseudo spiritualists accept a spiritual master who is not even fit to become a disciple because they want to keep him under their control. This is useless for spiritual realization.

One who imperfectly knows Kṛṣṇa consciousness cannot know Vedānta philosophy. A showy display of Vedānta study without Kṛṣṇa consciousness is a feature of the external energy, māyā, and as long as one is attracted by the inebrieties of this ever-changing material energy, he deviates from devotion to the Supreme Personality of Godhead. An actual follower of Vedānta philosophy is a devotee of Lord Viṣṇu, who is the greatest of the great and the maintainer of the entire universe. Unless one surpasses the field of activities in service to the limited, one cannot reach the unlimited. Knowledge of the unlimited is actual brahma-jñāna, or knowledge of the Supreme. Those who are addicted to fruitive activities and speculative knowledge cannot understand the value of the holy name of Lord Kṛṣṇa, which is always completely pure, eternally liberated and full of spiritual bliss. One who has taken shelter of the holy name of the Lord, which is identical with the Lord, does not have to study Vedānta philosophy, for he has already completed all such study.

One who is unfit to chant the holy name of Kṛṣṇa but thinks that the holy name is different from Kṛṣṇa and thus takes shelter of Vedānta study in order to understand Him must be considered a number one fool, as confirmed by Caitanya Mahāprabhu by His personal behavior, and philosophical speculators who want to make Vedānta philosophy an academic career are also considered to be within the material energy. A person who always chants the holy name of the Lord, however, is already beyond the ocean of nescience, and thus even a person born in a low family who engages in chanting the holy name of the Lord is considered to be beyond the study of Vedānta philosophy. In this connection Śrīmad-Bhāgavatam (3.33.7) states:

aho bata śva-paco ’to garīyān
yaj-jihvāgre vartate nāma tubhyam
tepus tapas te juhuvuḥ sasnur āryā
brahmānūcur nāma gṛṇanti ye te

“If a person born in a family of dog-eaters takes to the chanting of the holy name of Kṛṣṇa, it is to be understood that in his previous life he must have executed all kinds of austerities and penances and performed all the Vedic yajñas.” Another quotation states:

ṛg-vedo ’tha yajur-vedaḥsāma-vedo ’py atharvaṇaḥ
adhītās tena yenoktaṁ
harir ity akṣara-dvayam

“A person who chants the two syllables ha-ri has already studied the four Vedas — Sāma, Ṛg, Yajur and Atharva.

Taking advantage of these verses, there are some sahajiyās who, taking everything very cheaply, consider themselves elevated Vaiṣṇavas but do not care even to touch the Vedānta-sūtra or Vedānta philosophy. A real Vaiṣṇava should, however, study Vedānta philosophy, but if after studying Vedānta one does not adopt the chanting of the holy name of the Lord, he is no better than a Māyāvādī. Therefore, one should not be a Māyāvādī, yet one should not be unaware of the subject matter of Vedānta philosophy. Indeed, Caitanya Mahāprabhu exhibited His knowledge of Vedānta in His discourses with Prakāśānanda Sarasvatī. Thus it is to be understood that a Vaiṣṇava should be completely conversant with Vedānta philosophy, yet he should not think that studying Vedānta is all in all and therefore be unattached to the chanting of the holy name. A devotee must know the importance of simultaneously understanding Vedānta philosophy and chanting the holy names. If by studying Vedānta one becomes an impersonalist, he has not been able to understand Vedānta. This is confirmed in the Bhagavad-gītā (15.15). Vedānta means “the end of knowledge.” The ultimate end of knowledge is knowledge of Kṛṣṇa, who is identical with His holy name. Cheap Vaiṣṇavas (sahajiyās) do not care to study the Vedānta philosophy as commented upon by the four ācāryas. In the Gauḍīya-sampradāya there is a Vedānta commentary called the Govinda-bhāṣya, but the sahajiyās consider such commentaries to be untouchable philosophical speculation, and they consider the ācāryas to be mixed devotees. Thus they clear their way to hell.