Laksmi, the goddess of fortune, is the constant companion of Lord Visnu; they remain together constantly. One cannot keep Laksmi in one's home without Lord Visnu. To think that one can do so is very dangerous. To keep Laksmi, or the riches of the Lord, without the service of the Lord is always dangerous, for then Laksmi becomes the illusory energy. With Lord Visnu, however, Laksmi is the spiritual energy.
His Divine Grace A. C. BhaktivedantaSwami Prabhupada
Srimad-Bhagavatam 6.19.6, Purport
My dear Arjuna, only by undivided devotional service can I be understood as I am, standing before you, and can thus be seen directly. Only in this way can you enter into the mysteries of My understanding.
Lord Sri Krsna
Bhagavad-gita As It Is 11.54
The abode of Vrndavana is illuminated by innumerable moon rays of transcendental bliss. It is cooled by the nectarean mellows of ecstatic love. It is filled with many desire trees and chirping birds. Therefore who will not be attracted to Vrndavana, where Sri Radha and Krsna are eternally enjoying Their pastimes?
Srila Prabodhananda Sarasvati
Sri Vrndavana Mahimamrta 2.6
In Vaikuntha [the spiritual world] nothing exists but devotional service, rendered through sankirtana [the congregational chanting of God's names] and in many other forms. It goes on incessantly, with great enthusiasm, spreading the ecstasy of pure love.
Lord Siva
Sri Brhad-Bhagavatamrta 1.3.50
See how universal is the religion of Bhagavat [Srimad-Bhagavatam]. It is not intended for a certain class of Hindus alone, but it is a gift to the mankind at large in whatever country born, in whatever society bred, and of whatever culture produced. In short, Vaisnavism is the Absolute Love binding all men together into the Infinite, Unconditioned, and Absolute God (Krsna).
Srila Bhaktivinoda Thakura
The Bhagavat: Its Philosophy, Its Religion, Its Ethics & Its Theology
Scriptural evidence clearly indicates that for the yogis, jnanis, and karmis to become successful in their individual paths, their engagement in devotional service is imperative, whereas to attain perfection in the path of bhakti, which results in spontaneous love of Godhead, there is no need of yoga, jnana, karma, or any other process.
Srila Visvanatha Cakravarti Thakura
Madhurya Kadambini, First Shower