When Takṣaka saw even the most powerful serpents being burned in the blazing fire of that snake sacrifice, he was overwhelmed with fear and approached Lord Indra for shelter.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सर्पसत्रे समिद्धाग्नौ दह्यमानान् महोरगान् । दृष्ट्वेन्द्रं भयसंविग्नस्तक्षकः शरणं ययौ
sarpasatre samiddhāgnau dahyamānān mahoragān | dṛṣṭvendraṃ bhayasaṃvignastakṣakaḥ śaraṇaṃ yayau
SB 12.6.17