Shatapatha Brahmana 1.1.2.21

1.1.2.21

atha prāṅprekṣate | svarabhivikhyeṣamiti parivṛtamiva vā etadano bhavati tadasyaitaccakṣuḥ pāpmagṛhītamiva bhavati yajño vai svarahardevāḥ sūryastatsvarevaitadato bhivipaśyati

He now (whilst seated on the cart) looks towards east, with the text (Vâg. S. I, 11 b): 'May I perceive the light!' For that cart being covered up, its eye is thereby, as it were, affected with evil. Light, moreover, represents the sacrifice, the day, the gods, and the sun; so that he thereby perceives this same (fourfold) light.