Anyone whose work is not meant to elevate him to religious life, anyone whose religious ritualistic performances do not raise him to renunciation, and anyone situated in renunciation that does not lead him to devotional service to the Supreme Personality of Godhead must be considered dead, although breathing.

Srimati Devahuti
Srimad-Bhagavatam 3.23.56

With a single fragment of Myself, I pervade and support this entire universe.

Lord Sri Krsna
Bhagavad-gita 10.42

Anyone who has any desire or aspiration for satisfying his senses by becoming more and more important, either in the material sense or in the spiritual sense, cannot actually relish the really sweet taste of devotional service.

His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
The Nectar of Devotion, p. 33

Firm, ceaseless, and unshakable love of God which surpasses every other form of affection or attachment, and which is based on and inspired by a full knowledge of His transcendent majesty, is called bhakti; by that alone does one attain liberation by no other means.

Sripada Madhvacarya

A person who can understand that the Absolute Truth can exist with form and variety in a pure transcendental state can properly see that Visnu, His name, and His qualities are all one and inseparable from Him. This concept of Krsna with personality is actual knowledge. With this understanding one can take to chanting the holy name, knowing that it is Krsna Himself …

Srila Bhaktivinoda Thakura
The Holy Name

[O Lord,] when shall we engage as Your permanent eternal servants and always feel joyful to have such a perfect master?

Sri Yamunacarya
Stotra-ratna 43

When faults in others misguide and delude you have patience, introspect, find faults in yourself. Know that others cannot harm you unless you harm yourself.

Srila Bhaktisiddhanta Sarasvati Thakura
Discourse in Dhaka, Bangladesh, 1935

One should engage in penance and austerity to attain the divine position of devotional service. By such activity, one's heart is purified, and when one attains this position, he attains eternal, blissful life, which is transcendental to material happiness and which continues forever.

Lord Rsabhadeva
Srimad-Bhagavatam 5.5.1