Chānd-Mül, 1879-843. That flowed forth and went towards the sun. And that forms what we call the white (sukla) light of the sun.
Chānd-Śaṃ, 8th c. A.D.tāni vā etāni yajūṃṣyetaṃ yajurvedamabhyatapannityevamādi sarvaṃ samānam | madhvetadādityasya dṛśyate śuklaṃ rūpam || 2--3 ||
iti chāndogyopaniṣadi tṛtīyādhyāyasya dvitīyaḥ khaṇḍaḥ
http://www2.hf.uio.no/common/apps/permlink/permlink.php?app=polyglotta&context=record&uid=cc127fae-8e41-11ee-937a-005056a97067