Valmiki Ramayana Sundara Kanda Sarga 1 Shloka 157
Original Shlokaएवमुक्ता हनुमता सुरसा कामरूपिणी। अब्रवीन्नातिवर्तेन्मां कश्चिदेष वरो मम।।5.1.157।।
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हनुमता by Hanuman, एवम् in that way, उक्ता having been spoken, कामरूपिणी one who can assume any form at free will, सुरसा Surasa, अब्रवीत् said, कश्चित् no one, नातिवर्तेत cannot cross, एषः such, मम to me, वरः boon.
Having heard Hanuman, Surasa capable of taking any form at her free will told him that no one can cross (her region) as she had been given such a boon(by the Creator)৷৷