Śrīmad-Bhāgavatam · Text 1.8.15
Who is speaking and story frame
यद्यप्यस्त्रं ब्रह्मशिरस्त्वमोघं चाप्रतिक्रियम् ।
वैष्णवं तेज आसाद्य समशाम्यद् भृगूद्वह ॥ १५ ॥
yadyapy astraṁ brahma-śiras
tv amoghaṁ cāpratikriyam
vaiṣṇavaṁ teja āsādya
samaśāmyad bhṛgūdvaha
O Śaunaka, glory of Bhṛgu’s family, although the supreme brahmāstra weapon released by Aśvatthāmā was irresistible and without check or counteraction, it was neutralized and foiled when confronted by the strength of Viṣṇu [Lord Kṛṣṇa].
Read Śrīla Prabhupāda's purport on Vedabase.io