Valmiki Ramayana Sundara Kanda Sarga 49 Shloka 1

ततः then, भीमविक्रमः of fierce valour, सः हनुमान् that Hanuman, तस्य his, तेन कर्मणा by that act, विस्मितः astonished, रोषताम्राक्षः eyes red with anger, रक्षोधिपम् demon king, अवैक्षत beheld.

The highly courageous Hanuman, astonished at the action (of binding and dragging him to the court) by the demon king looked at him with eyes turned red in anger. Hanuman wonders at the splendour and glory of Ravana