Valmiki Ramayana Yuddha Kanda Sarga 13 Shloka 15
Original Shlokaइत्यहंतस्यशापस्यभीतःप्रसभमेवताम् । नारोहयेबलात्सीतांवैदेहींशयनेशुभे ।।6.13.15।।
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इति: thus, तस्य: that, शापस्य: on account of that curse, भीतः frightened, अहम् I, वैदेहीम् to Vaidehi, सीताम् Sita प्रसभमेव: perforce, बलात् by strength, शुभे: lustrous, शयने: bed नारोहये: not able to get.
"Thus, frightened on account of his curse, I do not perforce to get her to my lustrous bed."