Valmiki Ramayana Sundara Kanda Sarga 1 Shloka 137
Original Shlokaतद् द्वितीयं हनुमतो दृष्ट्वा कर्म सुदुष्करम्। प्रशशंसुः सुराः सर्वे सिद्धाश्च परमर्षयः।।5.1.137।।
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हनुमतः of Hanuman, तत् that, सुदुष्करम् most difficult, द्वितीयम् a second, कर्म task, दृष्ट्वा on seeing, सर्वे all, सुराः gods, सिद्धाश्च siddhas, परमर्षयः great sages, प्रशंशसुः praised him.
Gods, siddhas as well as the great sages praised him for the second great achievment of Hanuman, which is impossible for others to accomplish.