116
Śrīmad-Bhāgavatam
[Canto 6, Ch. 16]
नियम्य सर्वेन्द्रियबाह्यवर्तनं   जगद्गुरुं सत्वतशस्त्रविग्रहम् ॥३३॥
tataḥ samādhāya mano manīṣayā babhāṣa etat pratilabdha-vāg asau niyamya sarvendriya-bāhya-vartanam jagad-gurum sātvata-śāstra-vigraham
tataḥ —thereafter;  samādhāya —controlling;  manaḥ —the mind;  manīṣayā —by his intelligence;  babhāṣa —spoke;  etat —this;  pratilabdha —recovering;  vāk —speech;  asau —that one (King Citraketu);  niyamya —controlling;  sarva-indriya —of all the senses;  bāhya —external;  vartanam —the wandering;  jagat-gurum —who is the spiritual master of everyone;  sātvata —of devotional service;  śāstra —of the holy scriptures;  vigraham —the personified form.
TRANSLATION
Thereafter, by controlling his mind with his intelligence and thus restricting his senses from external engagements, he recovered suitable words with which to express his feelings. Thus he began offering prayers to the Lord, who is the personification of the holy scriptures [the  sātvata-saṁhitā  like the  Brahma-saṁhitā  and the  Nārada-pañcarātra ] and who is the spiritual master of all. He offered his prayers as follows.
PURPORT
One cannot offer prayers to the Lord with mundane words. One must become spiritually advanced by controlling the mind and senses. Then he can find suitable words to offer in prayers to the Lord. Quoting the following verse from the  Padma Purāṇa , Śrīla Sanātana Gosvāmī forbids us to sing any song not sung by authorized devotees.
avaiṣṇava-mukhodgīrṇam pūtam hari-kathāmṛtam śravaṇam naiva kartavyam sarpocchiṣṭam yathā payaḥ