Rudra-prasava-varṇana
The Manifestation and Naming of Rudra / Nīlalohita
तस्यादित्यतनुर्नाम्नः प्रथमा प्रथमस्य ते / इत्युक्ते तस्य यत्तेजश्चक्षुस्त्वासीत्प्रकाशकम्
tasyādityatanurnāmnaḥ prathamā prathamasya te / ityukte tasya yattejaścakṣustvāsītprakāśakam
Of your earliest names, the first is Ādityatanu; when this was spoken, his radiance became like an eye that gives light.