Indra has forced his way to Tvashtri's Soma and his powers flow out of every limb. Namuchi, seeing him undone, takes his vigour, Soma-drink and food through sura. Indra runs to the Ashvins and Sarasvati and recites his oath to Namuchi: not by day or night, not with staff or bow, palm or fist, dry or moist. For a share in what is recovered they pour out foam of water as a thunderbolt; at the end of night, before sunrise, Indra strikes off Namuchi's head. The Soma in the head is mixed with blood and has to be separated. The rite that repeats the healing is the Sautramani, 'well saved'.
North India · Aruna-Sarasvati confluence, Kurukshetra regionAll traditions
Told on Balarama's pilgrimage along the Sarasvati. Namuchi, afraid of Indra, hides in a ray of the sun. Indra offers friendship and swears not to kill him with anything wet or dry, by night or by day. Seeing a fog one day he cuts off Namuchi's head with foam. The head follows him crying 'slayer of a friend'. Brahma sends him to sacrifice and bathe at the confluence of the Aruna and the Sarasvati; he is freed of the sin, and Namuchi's head, falling into the same stream, wins eternal worlds.
What is different here:
Namuchi is innocent and a friend; no theft, no Ashvins or Sarasvati as weapon-makers; adds the pursuing head, Brahma's advice and the cleansing bath; the killing is counted as a grievous sin.
The hymns only allude. One verse says Indra tore off Namuchi's head with the foam of the waters. Another calls Namuchi a Dasa and says Indra pounded his head. A third says the Ashvins aided Indra in his affair with Namuchi of Asura birth, as parents aid a son, and that Sarasvati refreshed him after he had drunk.
What is different here:
No oath, no theft, no daybreak: only the foam, the head and the helpers.
Mahabharata, Udyoga Parva 10 and 16 (the motif moved to Vritra)
Pan-IndiaAll traditions
In Shalya's account to Yudhishthira the sages arrange a truce under which Vritra cannot be killed by anything dry or wet, by day or by night; Indra kills him at twilight on the sea shore with froth into which Vishnu has entered. Yet in the same book Brihaspati, praising Indra, lists Namuchi as a separate Asura he killed.
What is different here:
The oath and foam are attached to Vritra; Namuchi is only named in a list.
Sources: The Satapatha-Brahmana, tr. Julius Eggeling (Sacred Books of the East 12, 41); The Mahabharata, tr. K. M. Ganguli (1883-96), sections read for the Vedic layer; Hymns of the Rigveda, tr. R. T. H. Griffith (1896), hymns read for the Vedic layer