These servants of Indra found the sage sitting in meditation, having just offered his prescribed oblations into the sacrificial fire. His eyes closed in trance, he seemed invincible, like fire personified.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
हुत्वाग्निं समुपासीनं ददृशुः शक्रकिङ्कराः । मीलिताक्षं दुराधर्षं मूर्तिमन्तमिवानलम्
hutvāgniṃ samupāsīnaṃ dadṛśuḥ śakrakiṅkarāḥ | mīlitākṣaṃ durādharṣaṃ mūrtimantamivānalam
SB 12.8.23