It should be understood that sages, saintly persons and devotees are not unconcerned with the people’s welfare. Ordinary karmis are busy acquiring money for sense gratification, and ordinary jñanis are socially aloof when they speculate on liberation, but actual devotees and saintly persons are always anxious to see how the people can be made happy both materially and spiritually.
His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Srimad-Bhagavatam 4.14.7, Purport

It is useless trying independently to destroy ignorance and lust in the heart. But ignorance, lust, fruitive activities, all doubts, and material bondage are destroyed by the mercy of the Lord in the course of cultivating devotional service. The endeavor of karmis and jñanis does not yield such results. Therefore when one becomes neutral by giving up other desires and hopes, he attains pure devotional service to Krishna.
Srila Bhaktivinoda Thakura
Sri Bhaktyaloka, Chapter 7

Unless one is favored by a pure devotee, one cannot attain the platform of devotional service. To say nothing of krishna-bhakti, one cannot even be relieved from the bondage of material existence.
Sri Chaitanya Mahaprabhu
Sri Chaitanya-charitamrita, Madhya-lila 22.51

When the flame in a lamp burns the wick improperly, the lamp is blackened, but when the lamp is filled with ghee and is burning properly, there is bright illumination. Similarly, when the mind is absorbed in material sense gratification, it causes suffering, and when detached from material sense gratification it brings about the original brightness of Krsna consciousness.
Jada Bharata
Srimad-Bhagavatam 5.11.8

I desire to attain Your (Sri Sri Radha-Krishna’s) abode, where the wish-fulfilling cows, known as kamadhenu, are decorated with gracefully long horns. The eternal residence of Sri Krishna, the fulfiller of His devotees’ desires, is preeminently exhibiting itself in all grandeur.
Rig Veda 1.54.6
Quoted in Srila Bhaktivinoda Thakura’s Dasha-mula-tattva

If somehow or other by good fortune one develops faith in hearing and chanting My glories, such a person, being neither very disgusted with nor very much attached to material life, should achieve perfection through the path of loving devotion to Me.
Lord Sri Krishna
Srimad-Bhagavatam 11.20.8

[The Lord’s] transcendental form is the Absolute Truth, devoid of duality or of middle, beginning or end. It is self-effulgent, eternal and full of knowledge and bliss. Only through devotional service can one understand that form to be infallible.
Vasudeva Upanishad
Quoted in Srimad-Bhagavatam, Canto Eleven, Appendix