Valmiki Ramayana Aranya Kanda Sarga 57 Shloka 3
Original Shlokaस तस्य स्वरमाज्ञाय दारुणं रोमहर्षणम्। चिन्तयामास गोमायोस्स्वरेण परिशङ्कितः।।3.57.3।।
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सः he, तस्य गोमायोः the jackal's, दारुणम् dreadful, रोमहर्षणम् horripilating, स्वरम् tone, आज्ञाय recognising, स्वरेण voice, परिशङ्कितः doubting it, चिन्तयामास started worrying.
Rama knew it was the horrible, horripilating cry of a jackal which made him apprehensive . It made him think.