Mandukya Upanishad 40

40

Verse 10
svapnasthānastaijasa ukāro dvitīyā mātrotkarṣād
ubhayatvādvotkarṣati ha vai jñānasantatiṃ samānaśca
bhavati nāsyābrahmavitkule bhavati ya evaṃ veda ||

10. The sleeping state, the Brilliant, is the letter u, the second element, from utkarṣa ('exaltation') or from ubhayatvā ('intermediateness').

He exalts, verily, indeed, the continuity of knowledge; and he becomes equal (samāna); no one ignorant of Brahma is born in the family of him who knows this.