Valmiki Ramayana Kishkindha Kanda Sarga 25 Shloka 35

वनान्तरे in the midst of the forest, तासाम् of them, वानरीणाम् of female monkeys, रुदितशब्देन by their cries, सर्वतः all over, वनानि forest, गिरयश्चैव and the mountains, विक्रोशन्तीव looked as if they were mourning.

When the female monkeys were weeping in the midst of the forest, it looked as if the forest and the hills were also mourning.