Valmiki Ramayana Sundara Kanda Sarga 58 Shloka 28
Original Shlokaएवमुक्तस्सुरसया दशयोजनमायतः।।5.58.28।। ततोर्थगुणविस्तारो बभूवाहं क्षणेन तु।
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सुरसया when Surasa, एवम् in that way, उक्तः spoke, दशयोजनम् ten yojanas, आयतः in length, अहम् I, ततः then, क्षणेन in a moment, अर्थगुणविस्तारः fifteen yojanas, बभूव grew in size.
"When Surasa said this I who was ten yojanas in height increased by fifteen yojanas.