SB 6.9.1

śrī-śuka uvāca
tasyāsan viśvarūpasya
 śirāṁsi trīṇi bhārata
soma-pīthaṁ surā-pītham
 annādam iti śuśruma
Word for word: 
śrī-śukaḥ uvāca — Śrī Śukadeva Gosvāmī said; tasya — of him; āsan — there were; viśvarūpasya — of Viśvarūpa, the priest of the demigods; śirāṁsi — heads; trīṇi — three; bhārata — O Mahārāja Parīkṣit; soma-pītham — used for drinking the beverage soma; surā-pītham — used for drinking wine; anna-adam — used for eating; iti — thus; śuśruma — I have heard by the paramparā system.
Translation: 
Śrī Śukadeva Gosvāmī continued: Viśvarūpa, who was engaged as the priest of the demigods, had three heads. He used one to drink the beverage soma-rasa, another to drink wine and the third to eat food. O King Parīkṣit, thus I have heard from authorities.
Purport: 

One cannot directly perceive the kingdom of heaven, its king and other inhabitants, or how they perform their various engagements, for no one can go to the heavenly planets. Although modern scientists have invented many powerful space vehicles, they cannot even go to the moon, not to speak of other planets. By direct experience one cannot learn anything beyond the range of human perception. One must hear from authorities. Therefore Śukadeva Gosvāmī, a great personality, says, “What I am describing to you, O King, is what I have heard from authoritative sources.” This is the Vedic system. The Vedic knowledge is called śruti because it must be received by being heard from authorities. It is beyond the realm of our false experimental knowledge.