SB 10.1.21

giraṁ samādhau gagane samīritāṁ
 niśamya vedhās tridaśān uvāca ha
gāṁ pauruṣīṁ me śṛṇutāmarāḥ punar
 vidhīyatām āśu tathaiva mā ciram
Word for word: 
giram — a vibration of words; samādhau — in trance; gagane — in the sky; samīritām — vibrated; niśamya — hearing; vedhāḥ — Lord Brahmā; tridaśān — unto the demigods; uvāca — said; ha — oh; gām — the order; pauruṣīm — received from the Supreme Person; me — from me; śṛṇuta — just hear; amarāḥ — O demigods; punaḥ — again; vidhīyatām — execute; āśu — immediately; tathā eva — just so; — do not; ciram — delay.
Translation: 
While in trance, Lord Brahmā heard the words of Lord Viṣṇu vibrating in the sky. Thus he told the demigods: O demigods, hear from me the order of Kṣīrodakaśāyī Viṣṇu, the Supreme Person, and execute it attentively without delay.
Purport: 

It appears that the words of the Supreme Personality of Godhead can be heard in trance by competent persons. Modern science gives us telephones, by which one can hear sound vibrations from a distant place. Similarly, although other persons cannot hear the words of Lord Viṣṇu, Lord Brahmā is able to hear the Lord’s words within himself. This is confirmed in the beginning of Śrīmad-Bhāgavatam (1.1.1): tene brahma hṛdā ya ādi-kavaye. Ādi-kavi is Lord Brahmā. In the beginning of the creation, Lord Brahmā received the instructions of Vedic knowledge from Lord Viṣṇu through the medium of the heart (hṛdā). The same principle is confirmed herewith. While Brahmā was in trance, he was able to hear the words of Kṣīrodakaśāyī Viṣṇu, and he carried the Lord’s message to the demigods. Similarly, in the beginning, Brahmā first received the Vedic knowledge from the Supreme Personality of Godhead through the core of the heart. In both instances the same process was used in transmitting the message to Lord Brahmā. In other words, although Lord Viṣṇu was invisible even to Lord Brahmā, Lord Brahmā could hear Lord Viṣṇu’s words through the heart. The Supreme Personality of Godhead is invisible even to Lord Brahmā, yet He descends to this earth and becomes visible to people in general. This is certainly an act of His causeless mercy, but fools and nondevotees think that Kṛṣṇa is an ordinary historical person. Because they think that the Lord is an ordinary person like them, they are described as mūḍha (avajānanti māṁ mūḍhāḥ). The causeless mercy of the Supreme Personality of Godhead is neglected by such demoniac persons, who cannot understand the instructions of Bhagavad-gītā and who therefore misinterpret them.