Valmiki Ramayana Sundara Kanda Sarga 37 Shloka 50
Original Shlokaयुध्यमानस्य रक्षोभिस्तव तैः क्रूरकर्मभिः। प्रपतेयं हि ते पृष्ठाद्भयार्ता कपिसत्तम।।5.37.50।।
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कपिसत्तम O noble monkey, तव your, क्रूरकर्मभिः by those of wicked deeds, तैः by them, रक्षोभिः by the demons, युध्यमानस्य for you while engaged in fighting, भयार्ता out of fear, ते your, पृष्ठात् from the back, प्रपतेयं हि I will drop down.
"O noble monkey while you are engaged in fighting with those demons of wicked deeds, I may drop down out of fear.