The Supreme Lord can be pleased only by devotional service: therefore it is said here that the Lord is surely satisfied by devotion and nothing else. Quoting from the Gautamīya-tantra, the Hari-bhakti-vilāsa states:
tulasī-dala-mātreṇa
jalasya culukena vā
vikrīṇīte svam ātmānaṁ
bhaktebhyo bhakta-vatsalaḥ
"Śrī Kṛṣṇa, who is very affectionate toward His devotees, sells Himself to a devotee who offers merely a tulasī leaf and a palmful of water." The Supreme Lord is causelessly merciful upon His devotee, so much so that even the poorest of men can offer Him a little water and a flower in devotion and thus please Him. This is due to His affectionate dealings with His devotees.
(Srimad Bhagavatam------5:3:6-----purport).

In the process of worshiping the Deity it is sometimes enjoined that one worship the Deity within the mind. In the Padma Purāṇa, Uttara-khaṇḍa, it is said, "All persons can generally worship within the mind." The Gautamīya Tantra states, "For a sannyāsī who has no home, worship of the Deity within the mind is recommended." In the Nārada-pañcarātra it is stated by Lord Nārāyaṇa that worship of the Deity within the mind is called mānasa-pūjā, One can become free from the four miseries by this method. Sometimes worship from the mind can be independently executed.
(Srimad Bhagavatam------7:5:23-24-----purport).

"I offer my respectful obeisances unto my spiritual master, who with the torchlight of knowledge has opened my eyes, which were blinded by the darkness of ignorance." (Gautamīya Tantra) The guru's task is to open the disciple's eyes of knowledge. When the disciple is awakened from ignorance to knowledge, he can see the Supreme Personality of Godhead everywhere because the Lord actually is everywhere.
(Srimad Bhagavatam------8:1:11-----purport).

In this material world, every living entity is covered by the darkness of ignorance. Therefore the Vedas enjoin that one should approach the Supreme Lord through the spiritual master, who is described and offered prayers in the Gautamīya-tantra as follows:
oṁ ajñāna-timirāndhasya
jñānāñjana-śalākayā
cakṣur unmīlitaṁ yena
tasmai śrī-gurave namaḥ
"I offer my respectful obeisances unto my spiritual master, who with the torchlight of knowledge has opened my eyes, which were blinded by the darkness of ignorance."
(Srimad Bhagavatam------8:3:25-----purport).

"Śrī Kṛṣṇa, who is very affectionate toward His devotees, sells Himself to a devotee who offers Him merely a tulasī leaf and a palmful of water."
This is a verse from the Gautamīya-tantra.
(Sri Caitanya Caritamrta-----1:3:104-----translation and purport).

" 'The transcendental goddess Śrīmatī Rādhārāṇī is the direct counterpart of Lord Śrī Kṛṣṇa. She is the central figure for all the goddesses of fortune. She possesses all the attractiveness to attract the all-attractive Personality of Godhead. She is the primeval internal potency of the Lord.' "
This text is from the Bṛhad-gautamīya-tantra.
(Sri Caitanya Caritamrta-----1:4:83-----translation and purport).

" 'The transcendental goddess Śrīmatī Rādhārāṇī is the direct counterpart of Lord Śrī Kṛṣṇa. She is the central figure for all the goddesses of fortune. She possesses all the attraction to attract the all-attractive Personality of Godhead. She is the primeval internal potency of the Lord.' "
This text is found in the Bṛhad-gautamīya-tantra. For an explanation, see Ādi-līlā 4.83–95.
(Sri Caitanya Caritamrta-----2:23:68-----translation and purport).

When Kṛṣṇa sees that both Rādhārāṇī and Her associates are pleased by His association, He becomes more satisfied. Such association and loving reciprocation have nothing to do with material lust, although it resembles the material union between man and woman. It is only because that similarity is there that such reciprocation is sometimes called, in transcendental language, transcendental lust. As explained in Gautamīya-tantra (Bhakti-rasāmṛta-sindhu 1.2.285): "Lust means attachment to one's personal sense gratification. But as far as Rādhārāṇī and Her associates are concerned, they did not desire personal sense gratification. They only wanted to satisfy Kṛṣṇa."
(Teachings of Lord Caitanya).

According to great learned scholars, the whole Bhagavad-gītā contains many authorized prayers, especially in the Eleventh Chapter, where Arjuna prays to the universal form of the Lord. Similarly, in the Gautamīya-tantra all the verses are called prayers. Again, in Śrīmad-Bhāgavatam there are hundreds of prayers to the Lord. So a devotee should select some of these prayers for his recitation. In Skanda Purāṇa the glories of these prayers are stated as follows: "Devotees whose tongues are decorated always with prayers to Lord Kṛṣṇa are always given respect even by the great saintly persons and sages, and such devotees are actually worshipable by the demigods."
(Nectar of Devotion).