Valmiki Ramayana Yuddha Kanda Sarga 99 Shloka 21
Original Shlokaराक्षसस्यस्तनाभ्याशेमर्मज्ञोहृदयंप्रति ।।6.99.21।। इन्द्राशनिमस्पर्शं स मुष्टिंविन्यपातयत् ।
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मर्मज्ञः vital, सः he, राक्षसस्य Rakshasa's, स्तनाभ्याशे middle of the breasts, हृदयंप्रति into the heart, इन्द्राशनिसमस्पर्शम् equal to Indra's thunderbolt, मुष्टिम् fist, विन्यपातयत् pierced
Angada who knew the vital parts, pierced into the middle of the breasts of the Rakshasa into the heart by his fist which was equal to Indra's thunderbolt.