Valmiki Ramayana Yuddha Kanda Sarga 95 Shloka 11
Original Shlokaतन्निमित्तमिदंवैरंरावणेनकृतंमहत् । वधायसीतासासीतादशग्रीवेणरक्षसा ।।6.95.11।।
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तन्निमित्तम् for that reason, रावणेन by Ravana, महत् great, इदंवैरम् this enmity, कृतम् conceived, रक्षसा Rakshasa, दशग्रीवे ten headed, सासीता that Sita, वधाय borne away
"For that reason of Surpanakha, this enmity has been conceived by Ravana and Sita was borne away by the ten headed Rakshasa."