Śrīmad-Bhāgavatam · Text 6.12.7
Who is speaking and story frame
युयुत्सतां कुत्रचिदाततायिनां
जय: सदैकत्र न वै परात्मनाम् ।
विनैकमुत्पत्तिलयस्थितीश्वरं
सर्वज्ञमाद्यं पुरुषं सनातनम् ॥ ७ ॥
yuyutsatāṁ kutracid ātatāyināṁ
jayaḥ sadaikatra na vai parātmanām
vinaikam utpatti-laya-sthitīśvaraṁ
sarvajñam ādyaṁ puruṣaṁ sanātanam
Vṛtrāsura continued: O Indra, no one is guaranteed of being always victorious but the original enjoyer, the Supreme Personality of Godhead, Bhagavān. He is the cause of creation, maintenance and annihilation, and He knows everything. Being dependent and being obliged to accept material bodies, belligerent subordinates are sometimes victorious and sometimes defeated.
Read Śrīla Prabhupāda's purport on Vedabase.io