Valmiki Ramayana Yuddha Kanda Sarga 18 Shloka 13
Original Shlokaनवयंतत्कुलीनाश्चराज्यकाङ् क्षीचराक्षसः । पण्डिताहिभविष्यन्तितस्माद्ग्राह्योविभीषणः ।।6.18.13।।
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वयम् we, तत्कुलीनाःच: their clan, न: not, राक्षसः Rakshasas, राज्यकाङ् क्षीच: and desire for their (Rakshasa) kingdom, पण्डिताः learned, भविष्यन्ति: desires, तस्मात् on account of this cause, विभीषणः Vibheeshana, ग्राह्यः can be accepted.
"We do not belong to their clan. Among Rakshasas there are some learned ones. Vibheeshana has come because of his desire for their (Rakshasa) kingdom, perhaps ?"