Skandapurana 7.8.34_133

7.8.34_133

tenaiṣa na yathā devyā garbhe sañjāyate sutaḥ .
bhavecca tanayaḥ ślāghyo vara eṣa pradīyatām .. 13 6. .
tatognau tadadbhutaṃ tejo mayā putrārthamīśvari .
sutaste bhavitā śrīmān ṣaṭśirā dvādaśekṣaṇaḥ . . 1 37..

Therefore, grant this boon: so that a son may not be conceived in the womb of the goddess,
and yet a praiseworthy son may come to be."
Then, O lady, that wondrous fiery splendor was cast into the fire by me for the sake of a son.
Your glorious son will have six heads and twelve eyes.'