Valmiki Ramayana Kishkindha Kanda Sarga 16 Shloka 29

तयोः both, वृक्षैः with trees, सशाखैः with branches, शिखरैः with tops, वज्रकोटिनिभैः by those hard as tips of thunderbolts, नखैः with nails, मुष्टिभिः with fists, पद्भिः with feet, जानुभिः with knees, वृत्रवासवयोरिव like Vritra and Indra, पुनः पुनः again and again, घोरम् terrible, युद्धम् combat, अभूत् became.

Both like Vritra and Indra fought, hitting each other again and again with trees full of branches and tops, with their hard nails akin to thunderbolts and with their fists, knees, feet, etc.