Valmiki Ramayana Sundara Kanda Sarga 1 Shloka 20

तदा then, सविषैः by the venomous, कुपितैः by the angry, तैः by them, दष्टाः bitten, ताः महाशिलाः the huge rocks, पावकोददीप्ताः burnt by the flame, जज्वलुः burnt, सहस्रधा in a thousand pieces, बिभिदुश्च and broke.

Bitten by the venomous and angry snakes, the mountain was broken into a thousand pieces by the blazing flames.