A boar keeps the wealth of the Asuras beyond seven hills. Vishnu, the sacrifice hidden in the earth, tells Indra of it; Indra shoots through the hills with a bunch of darbha grass and Vishnu carries the spoil to the gods. In the Puranas the boar is Vishnu himself, who lifts the earth and kills Hiranyaksha.
The sacrifice goes away from the gods as Vishnu and enters the earth. The gods search hand in hand and Indra passes over him. Each asks who the other is: Indra is the one who smites in the stronghold, Vishnu the one who brings out of it. Vishnu says that a boar, a stealer of good things, keeps the wealth of the Asuras beyond seven hills, and tells Indra to strike it if he is what he claims. Indra plucks a bunch of darbha grass, pierces the seven hills and kills the boar, then tells Vishnu to fetch it. Vishnu carries it off, and so the gods win the Asuras' wealth; the word vedi is explained from this.
Two verses allude to the story. In one, Vishnu the wide strider, sent by Indra, brings a hundred buffaloes and a brew of rice and milk, and Indra kills the fierce boar. In the other, Vishnu drinks the Soma and carries off the cooked food, and one stronger than he shoots the wild boar through the mountain.
What is different here:
Allusion only: buffaloes and a rice brew as the spoil, the shot through the mountain; no hiding in the earth, no seven hills, no dialogue.
Vishnu, the sacrifice, hides from the gods and only Indra knows where he is. After the same exchange of names Vishnu tells Indra of a boar, a plunderer of goods, living on the far side of twenty-one ramparts of stone with the wealth of the Asuras. Indra breaks the ramparts and pierces the boar's heart, and Vishnu carries off what is found there.
What is different here:
Twenty-one stone ramparts instead of seven hills; the heart is pierced; no darbha grass. Known from Sayana's quotation as given by Muir.
Shatapatha Brahmana 14.1.2.11: Emusha raises the earth
Pan-IndiaAll traditions
In explaining why earth turned up by a boar is used in a rite, the text says the earth was at first only a span wide, and that a boar called Emusha raised her up; he was her lord Prajapati.
What is different here:
The boar is the earth-lifter and is Prajapati; no hunt, no Indra, no Vishnu. This telling belongs to the Prajapati record.
At the start of the age Narayana, as Brahma, sees that the earth lies under the waters and takes the form of a boar, as in earlier ages he had been a fish and a tortoise. Earth praises him. He lifts her on his tusks while the sages shelter among his bristles and hymn his body as the sacrifice: his feet the Vedas, his tusks the post, his tongue the fire. He sets the earth afloat on the ocean like a great ship and shapes its mountains.
What is different here:
The boar is Vishnu himself and saves the earth; the sacrifice is now his body; there is no demon in this chapter and no Indra.
Bhagavata Purana 3.13 and 3.17 to 3.19: Varaha and Hiranyaksha
Pan-IndiaVaishnava
The earth has sunk in a flood. While Brahma wonders how to raise her, a boar the size of a thumb-tip comes from his nostril and at once grows huge. He dives and lifts the earth on his tusks. Hiranyaksha, son of Diti, has been roaming with a mace in search of a fight; Varuna, too old for battle, has sent him to Vishnu. The demon taunts the boar as a beast of the water. The boar sets the earth on the water, gives her the power to float and fights him with the mace while Brahma and the sages watch; Brahma urges him to finish before evening. Trident and illusions fail, and the boar fells the demon with a blow at the root of the ear.
What is different here:
Adds the birth from Brahma's nostril and the duel with Hiranyaksha; the earth sinks by flood. Read on vedabase through summaries.
Sources: The Veda of the Black Yajus School (Taittiriya Sanhita), tr. A. B. Keith (1914); Vedic Mythology, A. A. Macdonell (1897); Hymns of the Rigveda, tr. R. T. H. Griffith (1896), hymns read for the Vedic layer; Original Sanskrit Texts, vol. 1 (2nd ed.), J. Muir; The Satapatha-Brahmana, tr. Julius Eggeling (Sacred Books of the East 12, 41); The Vishnu Purana, tr. H. H. Wilson (1840); Srimad-Bhagavatam (Bhaktivedanta Vedabase)