Valmiki Ramayana Sundara Kanda Sarga 1 Shloka 158
Original Shlokaतं प्रयान्तं समुद्वीक्ष्य सुरसा वाक्यमब्रवीत्। बलं जिज्ञासमाना वै नागमाता हनूमतः।।5.1.158।।
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नागमाता mother of serpents, सुरसा Surasa, हनूमतः of Hanuman, बलम् strength, जिज्ञासमाना वै desirous of knowing, प्रयान्तम् who was attempting to go away, तम् her, समुद्वीक्ष्य observing, वाक्यम् these words, अब्रवीत् said.
Surasa, mother of serpents, observing that Hanuman was attempting to escape, said this in order to gauge his strength: