Valmiki Ramayana Yuddha Kanda Sarga 19 Shloka 18
Original Shlokaयानिकर्मापदानानिरावणस्यविभीषण: । अख्यातानिचतत्त्वेनह्यवगच्छामितान्यहम् ।।6.19.18।।
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विभीषण: Vibheeshana, रावणस्य: Ravana's, यानि: those, कर्मापदानानि: actions followed, अख्यातानि: that which has been spoken, तानि: those, तत्त्वेन: in essence, अहम् अवगच्छामि: is known to me, हि: also.
"Vibheeshana Those actions resorted to by Ravana which have been spoken by you in essence are known to me."