Valmiki Ramayana Ayodhya Kanda Sarga 93 Shloka 22
Original Shlokaते समालोक्य धूमाग्रमूचुर्भरतमागताः। नामनुष्ये भवत्यग्नि र्व्यक्तमत्रैव राघवौ।।2.93.22।।
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ते they, धूमाग्रम् column of smoke, समालोक्य having seen, भरतम् to Bharata, आगताः returned, ऊचुः communicated, अमनुष्ये in a place bereft of men, अग्नि: fire, न भवति cannot exist, व्यक्तम् clearly, राघवौ Rama and Lakshmana, अत्रैव are here only.
Having seen the column of smoke, they returned and informed Bharata, saying, 'In a place bereft of men, fire cannot exist. Clearly Rama and Lakshmana must be here only.'