Mbh 12.166.4c

After the lapse of a thousand years, the puissant lord made arrangements for a grand sacrifice according to the ordinances laid down in the scriptures. The sacrificial altar became adorned with Rishis skilled in sacrifice and competent to perform all acts appertaining thereto, with faggots of sacrificial fuel, and with blazing fires. And it looked exceedingly beautiful in consequence of the sacrificial plates and vessels all made of gold. All the foremost ones among the gods took their seats on it. The platform was further adorned with Sadasyas all of whom were high regenerate Rishis. I have heard from the Rishis that soon something very awful occurred in that sacrifice. It is heard that a creature sprang (from the sacrificial fire) scattering the flames around him, and whose splendour equalled that of the Moon himself when he rises in the firmament spangled with stars. His complexion was dark like that of the petals of the blue lotus. His teeth were keen. His stomach was lean. His stature was tall. He seemed to be irresistible and possessed of exceeding energy. Upon the appearance of that being, the earth trembled. The Ocean became agitated with high billows and awful eddies. Meteors foreboding great disasters shot through the sky. The branches of trees began to fall down. All the points of the compass became unquiet. Inauspicious winds began to blow. All creatures began to quake with fear every moment. Beholding that awful agitation of the universe and that Being sprung from the sacrificial fire, the Grandsire said these words unto the great Rishis, the gods, and the Gandharvas. 'This Being was thought of by me. Possessed of great energy, his name is Asi (sword or scimitar). For the protection of the world and the destruction of the enemies of the gods, I have created him.