Valmiki Ramayana Yuddha Kanda Sarga 89 Shloka 26

ततः then, भीमनिःस्वनम् terrific sound, घोरम् dreadful, शरवर्षम् rain of arrows, मुञ्चतोः set free, आकाशे from the sky, सासारयोः having bow, नीलयोः dark, कालमेघयोरिव clouds like at the time dissolution, युध्यमानयोः started fighting, तयोः both of them, अथ now, महान् great, कालःlong, व्यत्ययात् from battlefield, तौ both, युद्धवैमुख्यम् not turned back, श्रमंवापि no fatigue, न उपजग्मुतुः not experienced

Just as dark clouds rain from the sky at the time of dissolution, the dreadful rain of arrows set free from the bows of both Lakshmana and Indrajith caused terrific sound. Both of them fought for long and did not turn back from the battlefield or experienced any fatigue