Valmiki Ramayana Yuddha Kanda Sarga 31 Shloka 20
Original Shlokaअथाध्वनिपरिश्रान्तमर्धरात्रेस्थितंबलम् । सुखसुप्तंसमासाद्यचारित्रंप्रथमंचरैः ।।6.31.20।।
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अथ and then, अध्वनि having walked all the way, परिश्रान्तम् taking rest, अर्धरात्रे midnight, सुखसुप्तम् slept well, स्थितम् stayed, बलम् army, प्रथमम् prime, समासाद्य sending, चरैः spies, चारित्रं all about them.
After having walked all the way they slept well and when they were sleeping at midnight, we found out all about them by sending prime spies.