Valmiki Ramayana Kishkindha Kanda Sarga 66 Shloka 32
Original Shlokaत्रिविक्रमे मया तात सशैलवनकानना। त्रिस्सप्तकृत्वः पृथिवी परिक्रान्ता प्रदक्षिणम्।।4.66.32।।
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तात dear, त्रिविक्रमे when Visnu took three strides, सशैलवनकानना with its mountains, trees and forests, पृथिवी the whole earth, मया by me, त्रिस्सप्तकृत्वः twenty one times, प्रदक्षिणम् परिक्रान्ता circumambulated.
'O dear when Visnu (Vamana incarnate) took three strides I circumambulated the whole earth including its mountains and trees twentyone times.