Valmiki Ramayana Ayodhya Kanda Sarga 18 Shloka 4
Original Shlokaतदपूर्वं नरपतेर्दृष्ट्वा रूपं भयावहम्। रामोऽपि भयमापन्नः पदा स्पृष्ट्वेव पन्नगम्।।2.18.4।।
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अपूर्वम् unprecedented, भयावहम् frightful, नरपतेः king's, तत् रूपम् that appearance, दृष्ट्वा having seen, रामोऽपि Rama also, पन्नगम् serpent, पदा with foot, स्पृष्ट्वेव touched, भयम् आपन्नः experienced fear.
Never before did Rama see such frightful appearance of his father. He was seized with fear as if he trampled a serpent.