Māndukya 1.04
स्वप्नस्थानोऽन्तप्रज्ञः। सप्ताङ्गः एकोनविंशतिमुखः प्रविविक्तभुक् तैजसो द्वितीयः पादः ॥४॥
In the state of dreams, the inner consciousness is seven-limbed, with nineteen mouths, enjoying subtle objects. The second aspect of the Lord during this process is known as 'taijasa', the luminous one.
Bhāshya 1.04
The impressions formed during the waking state shape the dream state, which is distinct, and is the cause of knowledge, the inner knower. The Lord's form known as 'taijasa', the luminous one, governs this process.
"जाग्रद्दर्शनसंस्काररूपत्वात् स्वप्नगं तु यत्। प्रविविक्तं तु तज्ज्ञानकारणोऽन्तर्ज्ञ उच्यते॥"
"The impressions formed during waking perception shape the dream state, which is distinct, yet it is referred to as the cause of knowledge, the inner knower."
इति वाराहे ॥४॥
- stated thus in the Varaha Purana.