Valmiki Ramayana Kishkindha Kanda Sarga 63 Shloka 6
Original Shlokaबुद्ध्यता च मया वीर्यं रावणस्य दुरात्मनः।।4.63.6।। पुत्रस्सन्तर्जितो वाग्भिर्न त्राता मैथिली कथम्।
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दुरात्मनः of the evilminded, रावणस्य Ravana's, वीर्यं बुद्ध्यता knowing his valour, मया by me, मैथिली princess from Mithila, कथम् how, न त्राता not protected, वाग्भिः with (harsh) words, पुत्रः son, संतर्जितः goaded.
'I goaded my son with harsh words saying, 'Knowing the valour of the evilminded Ravana, why did you not protect her (Sita)'