Valmiki Ramayana Aranya Kanda Sarga 4 Shloka 32
Original Shlokaप्रहृष्टरूपाविव रामलक्ष्मणौ विराधमुर्व्या प्रदरे निहत्य तौ। ननन्दतुर्वीतभयौ महावने शिलाभिरन्तर्दधतुश्च राक्षसम्।।3.4.32।।
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प्रहृष्टरूपाविव both joyful, रामलक्ष्मणौ Rama and Lakshmana, तं विराधम् that Viradha, उर्व्याः earth's, प्रदरे in the crevice, निहत्य after killing, वीतभयौ both fearlessly, महावने in the great forest, ननन्दतुः both rejoiced, राक्षसम् to the demon, शिलाभिः with rocks, अन्तर्दधतुश्च covered him.
Rama and Lakshmana were happy to consign Viradha's body to the pit after killing him. They filled the pit with rocks in the great forest without fear.