Valmiki Ramayana Yuddha Kanda Sarga 109 Shloka 24
Original Shlokaतान् दृष्टवारावणश्चक्रेस्वशरैःखंनिरन्तरम् ।।6.109.23।। ततस्थाभ्यांप्रमुक्तेनशरवर्षेणभास्वता । शरबद्धमिवाभातिद्वितीयंभास्वदम्भरम् ।।6.109.24।।
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रावणः Ravana, तान् them, दृष्टवा seeing, स्वशरैः those arrows, खम् sky, निरन्तरम् upto, चक्रे released, तदा then, ताभ्याम् both of them, प्रमुक्तेन released by, भास्वता resplendent, शरवर्षेण by the rain of arrows, भास्वत् resplendent, अम्भरम् space, शरबद्धम् enveloped network of arrows, द्वितीयम् इव like, अभाति seemed
Seeing the arrows in the sky released by Rama, even Ravana released arrows up to the sky. With the arrows released by both of them, the space became resplendent and by the network of arrows covering it seemed like another sky.