Skandapurana 1.3.6.105

1.3.6.105

mithilādhipateḥ kanyā yā uktā brahmavādibhiḥ..
sā brahmavidyāvataratsurāṇāṃ kāryyasiddhaye..
sītā jātā lāṃgalasya iyaṃ bhūmivikarṣaṇāt.. 8.105 ..

The daughter of the ruler of Mithilā, who is spoken of by the knowers of Brahman,
she, Brahmavidyā, descended for the accomplishment of the gods' purpose.
She was born as Sītā from the furrows made by a plow dragging the earth.