Śrī brahma-saṁhitā 5.28
Enlightened by the recollection of that Gāyatrī, embodying the three Vedas, Brahmā became acquainted with the expanse of the ocean of truth. Then he worshiped Śrī Kṛṣṇa, the essence of all Vedas, with this hymn.
Brahmā thought thus within himself, "By the recollection of kāma-gāyatrī it seems to me that I am the eternal maidservant of Kṛṣṇa." Though the other mysteries in regard to the condition of the maidservant of Kṛṣṇa were not revealed to him, Brahmā, by dint of his searching self-consciousness, became well acquainted with the ocean of truth. All the truths of the Vedas were revealed to him and with the help of those essences of the Vedas he offered this hymn to the Supreme Lord Śrī Kṛṣṇa. Śrīmān Mahāprabhu has taught this hymn to His favorite disciples in as much as it fully contains all the transcendental truths regarding the Vaiṣṇava philosophy. Readers are requested to study and try to enter into the spirit of his hymn with great care and attention, as a regular daily function.