Valmiki Ramayana Ayodhya Kanda Sarga 28 Shloka 12
Original Shlokaअहोरात्रं च सन्तोषः कर्तव्यो नियतात्मना। फलैर्वृक्षावपतितै स्सीते दुःखमतो वनम्।।2.28.12।।
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सीते O Sita, अहोरात्रम् night and day, नियतात्मना with senses under control, वृक्षावपतितैः fallen down the trees, फलैः with fruits, सन्तोषः satisfaction, कर्तव्यः to be derived, अतः therefore, वनम् forest life, दुःखम् is full of suffering.
With the senses under control night and day, O Sita, one must be satisfied with the fruits fallen from trees. Therefore, forest life is full of suffering.