Valmiki Ramayana Aranya Kanda Sarga 17 Shloka 14
Original Shlokaएवमुक्तस्तु राक्षस्या शूर्पणख्या परन्तपः।।3.17.14।। ऋजुबुद्धितया सर्वमाख्यातुमुपचक्रमे।
1 source checked for this shloka
राक्षस्या by the demoness, शूर्पणख्या by Surpanakha, एवम् in that way, उक्तः asked, परन्तपः a scorcher of foes, ऋजुबुद्धितया due to simplemindedness, सर्वम् everything, आख्यातुम् to tell, उपचक्रमे started.
Thus asked by the demoness Surpanakha, Rama, scorcher of foes began telling her everything due to his simplemindedness.