Valmiki Ramayana Sundara Kanda Sarga 15 Shloka 40
Original Shlokaतां समीक्षय विशालाक्षीं राजपुत्रीमनिन्दिताम्। तर्कयामास सीतेति कारणैरुपपादिभिः।।5.15.40।।
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विशालाक्षीम् largeeyed lady, अनिन्दिताम् blameless, तां राजपुत्रीम् that princess, समीक्ष्य after observing, उपपादिभिः by the right signs, कारणैः with reasons, सीतेति Sita only, तर्कयामास he came to conclusion after deliberation.
After close observation of different signs and deliberation with reasons he came to the conclusion that the largeeyed lady is the same blameless princess Sita.