Valmiki Ramayana Yuddha Kanda Sarga 57 Shloka 43

अथ and then वृक्षान् trees, आरुजतांचैव for the sake of fighting, गुर्वीः heavy, शिलाः rocks, आगृह्णताम् taking hold, हरीणाम् monkeys, सुतुमुलः exceedingly, घोषः tumultuous, समजायत arose.

And when the monkeys took hold of heavy rocks and trees for fighting exceedingly tumultuous clamor arose.