Mahabharata 1.43.9

1.43.9

tataḥ paramasaṃvignā svasā nāgapatestu sā |
atiduḥkhānvitā vācaṃ tamuvācaivamastviti || 9 ||

"And then the sister of the king of the snakes in great anxiety and grieving exceedingly, spoke unto him, saying, 'Be it so.' And moved by the desire of doing good to her relatives, that damsel, of unsullied reputation, began to attend upon her lord with the wakefulness of a dog, the timidity of a deer, and knowledge of signs possessed by the crow. And one day, after the menstrual period, the sister of Vasuki, having purified herself by a bath according to custom, approached her lord the great Muni; And thereupon she conceived. And the embryo was like unto a flame of fire, possessed of great energy, and resplendent as fire itself. And it grew like the moon in the bright fortnight.