Valmiki Ramayana Aranya Kanda Sarga 11 Shloka 27
Original Shlokaतथा संवसतस्तस्य मुनीनामाश्रमेषु वै।।3.11.27।। रमतश्चानुकूल्येन ययुस्संवत्सरा दश।
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तथा in that way, तस्य for him, आश्रमेषु in the hermitages, वसतः while he was living, रमतश्च and enjoying, दश ten, संवत्सराः years, आनुकूल्येन favourably, ययुः passed.
Thus enjoying their stay in the hermitages, Rama, Sita and Lakshmana spent ten favourable years.