Devotees should always be happy with all the dealings of their master, the Supreme Personality of Godhead. A devotee may be put into difficulty or opulence, but he should accept both as gifts of the Supreme Personality of Godhead and jubilantly engage in the service of the Lord in all circumstances.
His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Sri Chaitanya-charitamrita, Adi-lila 12.37, Purport

The word bhakti cannot be applied to anyone other than Krishna. Krishna is the only object of devotional service. Brahman is the object of impersonal knowledge, Paramatma of yoga, but Krishna the supreme object of service.
Srila Bhaktisiddhanta Sarasvati Thakura
Amrita Vani

Because I am transcendental, beyond both the fallible and the infallible, and because I am the greatest, I am celebrated both in the world and in the Vedas as that Supreme Person.
Lord Sri Krishna
Bhagavad-gita 15.18

In this world no one has any permanent relationship with anyone else, O King. We cannot stay forever even with our own body, what to speak of our wife, children, and the rest.
Sri Akrura to Dhritarashtra
Srimad-Bhagavatam 10.49.20

Certainly no means of perfection is superior to the worship of Sriman Madana-gopala’s [Krishna’s] lotus feet. That worship yields results far beyond what one could expect. It should be performed mainly through nama-sankirtana, along with reverence and affection for the many places of Sri Gopala’s pastimes, places one should regularly visit.
Sri Gopa-kumara
Brihad-bhagavatamrita 2.1.104-105

Thus indeed the breath of this Supreme Being constitutes the Rig Veda, Yajur Veda, Sama Veda, Atharvangirasa Veda, Itihasa, and Purana.
Mundaka Upanishad 2.1.2

Whatever we see in this world is but an expansion of various energies of the Supreme Personality of Godhead, who is like a fire that spreads illumination for a long distance although it is situated in one place.
Sri Parashara Muni
Vishnu Purana 1.22.56

If one very carefully and impartially discusses the characteristics, instructions, and scriptural conclusions of Sri Mahaprabhu Chaitanyadeva, one will be compelled to accept Him as sarvacharya, or the supreme authority on everything.
Srila Bhaktivinoda Thakura
Tattva-sutra 49

The scriptures stress the point that only animals, who are inferior to human beings, do not worship and serve the Supreme Lord. This proves that those who are really on the human platform naturally must develop devotion to the Supreme Lord.
Srila Vishvanatha Chakravarti Thakura
Madhurya-kadambini, First Shower