Valmiki Ramayana Kishkindha Kanda Sarga 43 Shloka 60
Original Shlokaस हि सोमगिरिर्नाम देवानामपि दुर्गमः। तमालोक्य ततः क्षिप्रमुपावर्तितुमर्हथ।।4.43.60।।
1 source checked for this shloka
सोमगिरिर्नाम Somagiri by name, सः that mountain, देवानामपि even for gods, दुर्गमः inaccessible, तम् them, आलोक्य after seeing, ततः that place, क्षिप्रम् at once, उपावर्तितुम् to return, अर्हथ not proper for you.
'It is difficult even for gods to reach Somagiri. You should return immediately after seeing that mountain.