SB 5.10.18

tad brūhy asaṅgo jaḍavan nigūḍha-
 vijñāna-vīryo vicarasy apāraḥ
vacāṁsi yoga-grathitāni sādho
 na naḥ kṣamante manasāpi bhettum
Synonyms: 
tat — therefore; brūhi — please speak; asaṅgaḥ — who have no association with the material world; jaḍa-vat — appearing like a deaf and dumb man; nigūḍha — completely hidden; vijñāna-vīryaḥ — who have full knowledge of the spiritual science and are thus very powerful; vicarasi — you are moving; apāraḥ — who possess unlimited spiritual glories; vacāṁsi — the words uttered by you; yoga-grathitāni — bearing the complete meaning of mystic yoga; sādho — O great saintly person; na — not; naḥ — of us; kṣamante — are able; manasā api — even by the mind; bhettum — to understand by analytical study.
Translation: 
My dear sir, it appears that the influence of your great spiritual knowledge is hidden. Factually you are bereft of all material association and fully absorbed in the thought of the Supreme. Consequently you are unlimitedly advanced in spiritual knowledge. Please tell me why you are wandering around like a dullard. O great saintly person, you have spoken words approved by the yogic process, but it is not possible for us to understand what you have said. Therefore kindly explain it.
Purport: 

Saintly people like Jaḍa Bharata do not speak ordinary words. Whatever they say is approved by great yogīs and those advanced in spiritual life. That is the difference between ordinary people and saintly people. The listener must also be advanced to understand the words of such exalted, spiritually advanced people as Jaḍa Bharata. Bhagavad-gītā was spoken to Arjuna, not to others. Lord Kṛṣṇa especially selected Arjuna for instruction in spiritual knowledge because Arjuna happened to be a great devotee and confidential friend. Similarly, great personalities also speak to the advanced, not to śūdras, vaiśyas, women or unintelligent men. Sometimes it is very risky to give great philosophical instructions to ordinary people, but Śrī Caitanya Mahāprabhu, for the benefit of the fallen souls of Kali-yuga, has given us a very nice instrument, the chanting of the Hare Kṛṣṇa mantra. The general mass of people, although śūdras and less, can be purified by chanting this Hare Kṛṣṇa mantra. Then they can understand the exalted philosophical statements of Bhagavad-gītā and Śrīmad-Bhāgavatam. Our Kṛṣṇa consciousness movement has therefore adopted the chanting of the Hare Kṛṣṇa mahā-mantra for the general masses. When people gradually become purified, they are instructed in the lessons of Bhagavad-gītā and Śrīmad-Bhāgavatam. Materialistic people like strī, śūdra and dvija-bandhu cannot understand words of spiritual advancement, yet one can take to the shelter of a Vaiṣṇava, for he knows the art of enlightening even śūdras in the highly elevated subject matter spoken in Bhagavad-gītā and Śrīmad-Bhāgavatam.