Ādi-līlā, Chapter 7
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Vedic  mantras , for it is a representation of Lord Kṛṣṇa, understanding of whom is the ultimate goal of the  Vedas , as stated in  Bhagavad-gītā  ( vedaiś ca sarvair aham eva vedyaḥ ). Māyāvādī philosophers cannot understand these simple facts explained in  Bhagavad-gītā , and yet they are very proud of being Vedāntīs. Sometimes, therefore, we refer to the Vedāntī philosophers as having no teeth ( danta  means “teeth,” and  ve  means “without”). The statements of the Śaṅkara philosophy, which are the teeth of the Māyāvādī philosopher, are always broken by the strong arguments of Vaiṣṇava philosophers such as the great  ācāryas , especially Rāmānujācārya. Śrīpāda Rāmānujācārya and Madhvācārya break the teeth of the Māyāvādī philosophers, who can therefore be called Vedāntīs in the sense of “toothless.”
The transcendental vibration  oṁkāra  is explained in  Bhagavad-gītā , Chapter Eight, verse thirteen:
om ity ekākṣaraṁ brahma vyāharan mām anusmaran yaḥ prayāti tyajan dehaṁ sa yāti paramāṁ gatim
“After being situated in the  yoga  practice and vibrating the sacred syllable  om , the supreme combination of letters, if one thinks of the Supreme Personality of Godhead and quits his body, he will certainly reach the spiritual planets.” If one actually understands that  oṁkāra  is the sound representation of the Supreme Personality of Godhead, whether he chants  oṁkāra  or the Hare Kṛṣṇa  mantra , the result is certainly the same.
The transcendental vibration of  oṁkāra  is further explained in  Bhagavad-gītā , Chapter Nine, verse seventeen:
pitāham asya jagato mātā dhātā pitāmahaḥ vedyaṁ pavitram oṁkāra ṛk sāma yajur eva ca
“I am the father of this universe, the mother, the support, and the grandsire. I am the object of knowledge, the purifier and the syllable  om . I am also the  Ṛg-veda ,  Sāma-veda  and  Yajur-veda .”
Similarly, the transcendental sound  om  is further explained in  Bhagavad-gītā , Chapter Seventeen, verse twenty-three:
oṁ-tat-sad iti nirdeśo brahmaṇas tri-vidhaḥ smṛtaḥ brāhmaṇās tena vedāś ca yajñāś ca vihitāḥ purā
“From the beginning of creation, the three syllables  om tat sat  have been used to indicate the Supreme Absolute Truth [Brahman]. They were uttered by  brāhmaṇas  while chanting Vedic hymns and during sacrifices for the satisfaction of the Supreme.”