Valmiki Ramayana Yuddha Kanda Sarga 64 Shloka 12
Original Shlokaयेनपूर्वंजनस्थानेबहवोऽतिबलाहताः । राक्षसाराघवंतंत्वंकथमेकोजयिष्यसि ।।6.64.12।।
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पूर्वम् in the past, जनस्थाने Janasthana, येन he who, अतिबलाः exceeding might, बहवः many, राक्षसाः Rakshasas, हताः killed, तम् him, राघवम् Raghava, त्वम् you, एकः single handed, कथम् how, जयिष्यसि won.
"How is it possible for you single handed to win Raghava of exceeding might, who killed many Rakshasas in the past at Janasthana?"