Adi Parva - Astika Parva 40

"Sauti said, 'The snake-sacrifice then commenced according to due form.
And the sacrificial priests, competent in their respective duties
according to the ordinance, clad in black garments and their eyes red
from contact with smoke, poured clarified butter into the blazing fire,
uttering the appropriate mantras. And causing the hearts of all the
snakes to tremble with fear, they poured clarified butter into the mouth
of Agni uttering the names of the snakes. And the snakes thereupon began
to fall into the blazing fire, benumbed and piteously calling upon one
another. And swollen and breathing hard, and twining each other with
their heads and tails, they came in large numbers and fell into the fire.
The white, the black, the blue, the old and the young--all fell alike
into the fire, uttering various cries. Those measuring a krosa, and those
measuring a yojana, and those of the measure of a gokarna, fell
continuously with great violence into that first of all fires. And
hundreds and thousands and tens of thousands of snakes, deprived of all
control over their limbs, perished on that occasion. And amongst those
that perished, there were some that were like horses, other like trunks
of elephants, and others of huge bodies and strength like maddened
elephants Of various colours and virulent poison, terrible and looking
like maces furnished with iron-spikes, of great strength, ever inclined
to bite, the snakes, afflicted with their mother's curse, fell into the
fire.'"