Valmiki Ramayana Sundara Kanda Sarga 10 Shloka 53
Original Shlokaस तां दृष्ट्वा महाबाहुर्भूषितां मारुतात्मजः। तर्कयामास सीतेति रूपयौवनसम्पदा।।5.10.53। हर्षेण महता युक्तो ननन्द हरियूथपः।
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महाबाहुः with long arms, सः मारुतात्मजः that son of the Windgod, भूषिताम् decorated, ताम् her, दृष्ट्वा on seeing, रूपयौवनसम्पदा by the wealth of her beauty and charm, सीतेति 'this is Sita', तर्कयामास deliberated, हरियूथपः chief of vanara, महता with great, हर्षेण joy, युक्तः endowed, ननन्द rejoiced.
On seeing her embellished with ornaments, beauty and charm, the long armed son of the Windgod, the chief of the vanaras thought her to be Sita and rejoiced.