The engagements of the Great Souls, freed from delusion and perfect in their realization of God, are described here: "Satatam kirtayanto mam"—they are always (satatam) chanting (kirtayanto) My glories, and "nitya-yukta upasate"—always worshiping Me.
So I do not know how you can say "indisputable." And, if you want reference from the Vedas, I can give you many. In the Vedas the chief transcendental vibration Omkara is also Krishna. Pranaba Omkara is the divine substance of the Vedas. Following the Vedas means chanting the Vedic Mantras, and no Vedic Mantra is complete without Omkara. In the Mandukya Upanisad, Omkara is stated to be the most auspicious sound representation of the Supreme Lord. This is also confirmed again in the Atharva Veda. Omkara is the sound representation of the Supreme Lord and is therefore the principal word in the Vedas. In this connection, the Supreme Lord Krishna says, "Pranaba Sarva Vedesu" (B.G. 7:8)—"I am the syllable Om in all the Vedic Mantras."
Furthermore, in the 15th verse of chapter 15, Bhagavad-gita, Krishna says, "I am seated in everyone's heart. By all the Vedas I am to be known; I am the Compiler of Vedanta and I know Veda as it is." The Supreme Lord, seated in everyone's heart, is described in both the Mundaka and Svetasvetara Upanisads; "Dwa suparna sayuja sakhaya . ." The Supreme Lord and the individual spirit soul are sitting in the body as two friendly birds in a tree. The one bird is eating the fruits of the tree or reactions of material activities and the other bird, the Supersoul, is witnessing.
The goal of Vedantic study, therefore, is to know the Supreme Lord Krishna. This point is stressed in Bhagavad-gita chapter 8, verse 13, where it is stated that by the mystic yoga process, ultimately vibrating the sacred syllable Om, one attains to His Supreme Spiritual Planet. In the Vedanta Sutras, which you have certainly read, the fourth chapter, fourth Adhikaran twenty-second Sutra states it positively; "Anavritti sabat . . ."—By sound vibration one becomes liberated. By devotional service, by understanding well what is the Supreme Personality of Godhead, anyone who goes to His Abode never comes back again to this material condition. How is it possible? The answer is, simply by chanting His name constantly.
This is accepted by the exemplary disciple, Arjuna, who has perfectly learned the conclusion of spiritual science from the Yogisvara, master of mystic knowledge, Krishna, recognizing Krishna to be the Supreme Brahman, Arjuna addresses Him: "Sthane Hrsikesa . . ." (B.G. 11:36)—"the world becomes joyful hearing Your Names; and thus do all become attached to You." The process of chanting is herein authorized as the direct means of contacting the Supreme Absolute Truth the Personality of Godhead. Simply by chanting the Holy Name, Krishna, the soul is attracted by the Supreme Person, Krishna, for going home, back to Godhead.
In the Narada Pancaratra it is stated that all the Vedic rituals, Mantras and understanding are compressed into the eight words; Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare. Similarly, in the Kalisantra Upanisad it is stated that these sixteen words Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare, Hare Rama, Hare Rama, Rama Rama, Hare Hare are especially meant for counteracting the degrading and contaminating influence of this materialistic age of Kali.
All these points are elaborately presented in my book, The Teachings of Lord Caitanya.
The process of chanting is, therefore, not only the sublime method for practical perfection of life, but it is the authorized Vedic principle and inaugurated by the greatest Vedic scholar and devotee (Whom we consider as an incarnation of Krishna), Lord Caitanya, and we are simply following His authorized footsteps.
The scope of the Krishna Consciousness Movement is Universal. The process for regaining one's original spiritual status or eternal life full with bliss and knowledge, is not abstracted dry theorizing. Spiritual life is not described in the Vedas as theoretical, dry or impersonal. The Vedas aim at the inculcation of pure love of God only, and this harmonized conclusion is practically realized by the Krishna Consciousness Movement or chanting Hare Krishna Mantra.
As the goal of Spiritual realization is only one, love of God, so the Vedas stand as a single comprehensive whole in the matter of transcendental understanding. Only the incomplete views of various parties apart from the bona fide Vedic lines of teaching, give a rupturous appearance to the Bhagavad-gita. The reconciliative factor adjusting all apparently diverse propositions of the Vedas is the essence of the Veda or Krishna Consciousness (Love of God).