Mahabharata 3.214.18

3.214.18

dvitīyāyāmabhivyaktastṛtīyāyāṃ śiśurbabhau |
aṅgapratyaṅgasaṃbhūtaścaturthyāmabhavadguhaḥ || 18 ||

Markandeya continued, 'Then assuming the disguise of a winged creature, she went out of the forest and reached the White Mountain begirt with clumps of heath and other plants and trees, and guarded by strange seven-headed serpents with poison in their very looks, and abounding with Rakshasas, male and female Pisachas, terrible spirits, and various kinds of birds and animals. That excellent lady quickly ascending a peak of those mountains, threw that semen into a golden lake. And then assuming successively the forms of the wives of the high-souled seven Rishis, she continued to dally with Agni. But on account of the great ascetic merit of Arundhati and her devotion to her husband (Vasishtha), she was unable to assume her form. And, O chief of Kuru's race, the lady Swaha on the first lunar day threw six times into that lake the semen of Agni. And thrown there, it produced a male child endowed with great power. And from the fact of its being regarded by the Rishis as cast off, the child born therefrom came to be called by the name of Skanda. And the child had six faces, twelve ears, as many eyes, hands, and feet, one neck, and one stomach. And it first assumed a form on the second lunar day, and it grew to the size of a little child on the third. And the limbs of Guha were developed on the fourth day. And being surrounded by masses of red clouds flashing forth lightning, it shone like the Sun rising in the midst of a mass of red clouds.