SB 6.9.1
sri-suka uvaca
tasyasan visvarupasya
siramsi trini bharata
soma-pitham sura-pitham
annadam iti susruma
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Sri Sukadeva Gosvami continued: Visvarupa, 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 Pariksit, thus I have heard from authorities.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
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 Sukadeva Gosvami, 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 sruti because it must be received by being heard from authorities. It is beyond the realm of our false experimental knowledge.