Valmiki Ramayana Aranya Kanda Sarga 59 Shloka 19
Original Shlokaरिपुः प्रच्छन्नचारी त्वं मदर्थमनुगच्छसि। राघवस्यान्तरप्रेप्सुस्तथैनं नाभिपद्यसे।।3.59.19।।
1 source checked for this shloka
प्रच्छन्नचारी in disguise, रिपुः enemy, त्वम् you, राघवस्य Rama's, अन्तरप्रेप्सुः waiting for an opportunity, मदर्थम् for my sake, अनुगच्छसि are following, तथा like this, एनम् him, नाभिपद्यसे not going now.
'You are an enemy moving in disguise with an interest in me. You are waiting for an opportunity to set aside Rama. That is why you are not rushing to him.'