Valmiki Ramayana Yuddha Kanda Sarga 68 Shloka 6
Original Shlokaतंश्रुत्वाविनिहतंसङ्ख्येकुम्भकर्णंमहाबलम् । रावणश्शोकसन्तप्तोमुमोह च पपात च ।।6.68.6।।
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रावणः Ravana, सङ्ख्ये hearing, महाबलम् of great strength, कुम्भकर्णम् Kumbhakarna, विनिहतम् slain, तम् श्रुत्वा hearing that, शोकसन्तप्तः immersed in grief, मुमोह च पपात च became deluded and fell down.
Hearing that Kumbhakarna of great strength was slain, Ravana immersed in grief became deluded and fell.