In ignorance, people are imagining the form of the Lord; sometimes He has no form and sometimes He has form, according to their different imaginations. But the presentation of Krishna in the Brahma-samhita is vijnana – scientific, experienced knowledge given by Lord Brahma and accepted by Lord Chaitanya. There is no doubt about it. Sri Krishna’s form, Sri Krishna’s flute, Krishna’s color – everything is reality.
His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Srimad-Bhagavatam 10.2.35, Purport

One who sacrifices his happiness for Krishna’s happiness and who remains always engaged in Krishna’s service by renouncing his own enjoyment for Krishna’s pleasure is a devotee. He certainly attains auspiciousness. Devotional service is the propensity to give Krishna pleasure. The endeavor to make oneself happy is nondevotional service and is the source of misery.
Srila Bhaktisiddhanta Sarasvati Thakura
Amrita-vani: Nectar of Instructions for Immortality

Having awakened faith in the narrations of My glories, being disgusted with all material activities, knowing that all sense gratification leads to misery, but still being unable to renounce all sense enjoyment, My devotee should remain happy and worship Me with great faith and conviction. Even though he is sometimes engaged in sense enjoyment, My devotee knows that all sense gratification leads to a miserable result, and he sincerely repents such activities.
Lord Sri Krishna
Srimad-Bhagavatam 11.20.27–28

Bhakti alone brings one to Him. Bhakti alone shows Him. The Supreme Lord subordinates Himself to bhakti. Indeed, bhakti is supreme.
Vishnu-sahasra-nama-stotra 32

O Maitreyi, one should see, hear, remember, and inquire about the Supreme Personality of Godhead.
Brihad-aranyaka Upanishad 2.4.5

Knowing Him, one transcends death. There is no other path for attaining this goal.
Svetashvatara Upanishad 3.8

Vaikuntha is the abode of countless spiritual qualities, a world of un-approachable supreme light. It cannot be perceived by material senses, nor compared to anything known. It is supremely ecstatic and beyond the scope of the senses.
Brahmanda Purana

All things that exist have their own potencies, understandable only by transcendental intelligence. O best of ascetics, the Supreme Truth also has His real potencies for creation and other functions, and these belong to Him as the power of heat belongs to fire.
Vishnu Purana 1.3.2

O my Lord, O Supreme Personality of Godhead, will I again be able to be a servant of Your eternal servants who find shelter only at Your lotus feet? O Lord of my life, may I again become their servant so that my mind may always think of Your transcendental attributes, my words always glorify those attributes, and my body always engage in the loving service of Your Lordship?
Vritrasura (formerly King Chitraketu)
Srimad-Bhagavatam 6.11.24