Valmiki Ramayana Bala Kanda Sarga 24 Shloka 5
Original Shlokaततश्शुश्राव वै शब्दमतिसंरम्भवर्धितम्। मध्यमागम्य तोयस्य सह राम:कनीयसा।।1.24.5।।
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तत: then, राम: Rama, तोयस्य of the water, मध्यम् midst, आगम्य having come, अतिसंरम्भवर्धितम् greatly augmented by the speed, शब्दम् thunderous noise, कनीयसा सह with his younger brother, शुश्राव heard.
As they reached the midstream, Rama and his younger brother heard a sound greatly augmented by the speed (of the river).