Valmiki Ramayana Ayodhya Kanda Sarga 19 Shloka 37
Original Shlokaउचितं च महाबाहुर्नजहौहर्षमात्मनः। शारद स्समुदीर्णांशुश्चन्द्रस्तेज इवात्मजम्।।2.19.37।।
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महाबाहुः mightyarmed, समुदीर्णांशुः with profuse radiance, शारदः autumnal, चन्द्र: the Moon, आत्मजम् his own, तेज इव like brightness, आत्मनः his own, उचितम् fitting, हर्षम् cheer, न जहौ did not leave.
The mightyarmed (Rama) did not leave his habitual cheerfulness like the autumnal Moon his own brightness.