Rudra-prasava-varṇana
The Manifestation and Naming of Rudra / Nīlalohita
विवेश तत्तदादित्यं तस्माद्रुद्रो ह्यसौ स्मृतः / उद्यतमस्तं यन्तं च वर्जयेद्दर्शनेरविम्
viveśa tattadādityaṃ tasmādrudro hyasau smṛtaḥ / udyatamastaṃ yantaṃ ca varjayeddarśaneravim
That radiance entered into that very Āditya; therefore he is remembered as Rudra. One should avoid gazing directly at the Sun at its rising, setting, and when it stands overhead.