Varuna cures his son Bhrigu of pride by sending him to see men eaten by the things they consumed in life, then explains the sights as the daily fire offering.
Varuna, aware that his son deems himself superior in knowledge, sends him through the quarters. Bhrigu sees men dismembering men in the east and south, men silently eaten in the west, men eaten crying in the north, and in the north-east two women with a black, yellow-eyed man holding a staff. Terrified, he goes home and says there is nothing to study. Varuna explains the sights as trees, cattle, herbs, waters, Belief, Unbelief and Wrath, each subdued by a part of the Agnihotra.
Bhrigu thinks himself above his father, the gods and his fellow students. Varuna seizes his breaths; he faints and goes to the other world. He sees a man cut up and eat a man, a man eat one who cries out, a man eat one who is silent, two women guarding a great treasure, a river of blood guarded by a black naked man with a club beside a river of ghee from which golden men draw all desires with golden cups, and five lotus-filled rivers of honey with music and Apsarases. Varuna explains: trees, animals, and rice and barley eat in turn those who used them without the Agnihotra; the women are Faith and Non-Faith; the black man is Wrath; the five rivers are Varuna's own worlds, won only by the Agnihotra. Bhrigu resolves to set up his fires.
What is different here:
The journey happens in a faint after Varuna takes his breath; six sights instead of five; adds the rivers of blood and ghee and Varuna's honey worlds; names the victims as trees, animals, rice and barley; ends with Bhrigu founding his fire.
Bhrigu asks his father Varuna to teach him Brahman. Varuna names food, breath, eye, ear, mind and speech, and says: that from which beings are born, by which they live and into which they enter at death is Brahman. Bhrigu performs tapas and concludes in turn that it is food, breath, mind and understanding; each time Varuna tells him to seek it by tapas. Finally he perceives that bliss is Brahman. This is called the knowledge of Bhrigu and Varuna.
What is different here:
No pride, no journey and nothing fearful; the same father and son, the same method of sending the son away to find out, and the answer is knowledge of Brahman, not a rite.
Sources: The Satapatha-Brahmana, tr. Julius Eggeling (Sacred Books of the East 12, 41); Extracts from the Jaiminiya-Brahmana and Upanishad-Brahmana, Hanns Oertel, Journal of the American Oriental Society 15 (1893), pp. 233-251; The Upanishads, tr. F. Max Muller (Sacred Books of the East 1 and 15)