From Shvetâshvatara-Upanishad, VI. 17-18.
स तन्मयो ह्यमृत ईशसंस्थो ज्ञः सर्वगो भुवनस्यास्य गोप्ता।
य ईशेऽस्य जगतो नित्यमेव नान्यो हेतुर्विद्यत ईशनाय॥
यो ब्रह्माणं विदधाति पूर्व यो वै वेदांश्च प्रहिणोति तस्मै।
तं ह देवं आत्मबुध्दिप्रकाशं मुमुक्षुर्वै शरणमहं प्रपद्ये॥
"He is the Soul of the Universe; He is Immortal; His is the Rulership; He is the All-knowing, the All-pervading, the Protector of the Universe, the Eternal Ruler. None else is there efficient to govern the world eternally. He who at the beginning of creation projected Brahmâ (i.e. the universal consciousness), and who delivered the Vedas unto him — seeking liberation I go for refuge unto that effulgent One, whose light turns the understanding towards the Âtman."
DEFINITION OF BHAKTI
Bhakti-Yoga is a real, genuine search after the Lord, a search beginning, continuing, and ending in love. One single moment of the madness of extreme love to God brings us eternal freedom. "Bhakti", says Nârada in his explanation of the Bhakti-aphorisms, "is intense love to God"; "When a man gets it, he loves all, hates none; he becomes satisfied for ever"; "This love cannot be reduced to any earthly benefit", because so long as worldly desires last, that kind of love does not come; "Bhakti is greater than karma, greater than Yoga, because these are intended for an object in view, while Bhakti is its own fruition, its own means and its own end."
Bhakti yoga, one of the four main yogic paths to enlightenment, is the easiest of all to master. Hatha and raja yoga require much inner strength and physical health to reach one's goal. And jnana yoga requires a keen, subtle intellect. But the only requirement for bhakti yoga is an open, loving heart. Because the theory behind the practice is so simple, everyone can practice bhakti yoga.
Bhakti means devotion to the Lord. One need only surrender all doubts, fears and worries and express genuine love and devotion to the almighty Lord of The Universe.
Bhakti has been the one constant theme of our sages. Apart from the special writers on Bhakti, such as Shândilya or Narada, the great commentators on the Vyâsa-Sutras, evidently advocates of knowledge (Jnâna), have also something very suggestive to say about love. Even when the commentator is anxious to explain many, if not all, of the texts so as to make them import a sort of dry knowledge, the Sutras, in the chapter on worship especially, do not lend themselves to be easily manipulated in that fashion.
The one great advantage of Bhakti is that it is the easiest and the most natural way to reach the great divine end in view.
In commenting on the Sutra of Patanjali, Ishvara pranidhânâdvâ, i.e. "Or by the worship of the Supreme Lord" — Bhoja says, "Pranidhâna is that sort of Bhakti in which, without seeking results, such as sense-enjoyments etc., all works are dedicated to that Teacher of teachers." Bhagavan Vyâsa also, when commenting on the same, defines Pranidhana as "the form of Bhakti by which the mercy of the Supreme Lord comes to the Yogi, and blesses him by granting him his desires". According to Shândilya, "Bhakti is intense love to God." The best definition is, however, that given by the king of Bhaktas, Prahlâda:
या प्रीतिरविवेकानां विषयेष्वनपायिनी।त्वामनुस्मरतः सा मे
हृदयान्मापसर्पतु॥
First References
Second Reference