Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 55: King Viśvāmitra Obtains Divine Weapons
Text 1.55.5-6

दृष्ट्वा निषूदितं सैन्यं वसिष्ठेन महात्मना।
विश्वामित्रसुतानां तु शतम्नानाविधायुधम्॥

अभ्यधावत्सुसंक्रुद्धं वसिष्ठं जपतां वरम्॥
हुंकारेणैव तान्सर्वान्ददाह भगवानृषिः॥

dṛṣṭvā niṣūditaṁ sainyaṁ vasiṣṭhena mahātmanā
viśvāmitra-sutānāṁ
tu śatam nānā-vidhāyudham

abhyadhāvat susaṁkruddhaṁ vasiṣṭhaṁ japatāṁ varam
huṁ-kāreṇaiva
tān sarvān dadāha bhagavān ṛṣiḥ

dṛṣṭvā = seeing; niṣūditam = annihilated; sainyam = the army; vasiṣṭhena = Vasiṣṭha; mahā-ātmanā = by the the greatly intelligent; viśvāmitra-sutānām tu śatam = a hundred sons of Viśvāmitra; nānā-vidha-āyudham = equipped with various kinds of weapons; abhyadhāvat = dashed towards; susaṁkruddham = in great anger; vasiṣṭham = Vasiṣṭha; japatām varam = the best of mantra chanters; huṁ-kāreṇa eva = by simply uttering “huṁ”; tān sarvān dadāha = burnt all of them; bhagavān ṛṣiḥ = that powerful sage.

Seeing the army annihilated by the the greatly intelligent Vasiṣṭha, a hundred sons of Viśvāmitra equipped with various kinds of weapons dashed towards Vasiṣṭha, the best of mantra chanters, in great anger. By simply uttering “huṁ,” that powerful sage burnt all of them.

Viśvāmitra’s sons dashed towards Vasiṣṭha because he was the cause of the destruction of their army. They themselves were burnt up by Vasiṣṭha’s utterance of “huṁ” because he was the best of chanters.