Valmiki Ramayana Yuddha Kanda Sarga 111 Shloka 17
Original Shlokaस वज्रइवदुर्धर्षोवज्रिबाहुविसर्जितः । कृतान्तइवचावार्योन्यपतद्रावणोरसि ।।6.111.17।।
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वज्रिबाहुविसर्जितः released from thunderbolt hurled by the arm of Indra, वज्रःइव like thunderbolt, दुर्धर्षः difficult, कृतान्तःइव capable of bringing to an end, अवार्यः prevent, सः that, रावणोरसि into Ravana's chest, न्यपतत् penetrated
Like the thunderbolt hurled by the arm of Indra, difficult to obstruct, capable of bringing life to an end, that arrow released by Rama penetrated into Ravana's chest.