Valmiki Ramayana Sundara Kanda Sarga 2 Shloka 27
Original Shlokaआगत्यापीह हरयो भविष्यन्ति निरर्थकाः। न हि युद्धेन वै लङ्का शक्या जेतुं सुरैरपि।।5.2.27।।
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हरयः monkeys, इह here, आगत्यापि even after coming here, निरर्थकाः will not serve any purpose, भविष्यन्ति will be, लङ्का Lanka, युद्धेन by war, सुरैरपि even by gods, जेतुम् to win, न शक्या हि not possible.
'It is not possible for monkeys to come here and even if they do, it is no use. Lanka is invincible even to the gods in war.