Valmiki Ramayana Aranya Kanda Sarga 7 Shloka 13
Original Shlokaतमुग्रतपसायुक्तं महर्षिं सत्यवादिनम्। प्रत्युवाचात्मवान्रामो ब्रह्माणमिव काश्यपः।।3.7.13।।
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आत्मवान् selfpossessed, रामः Rama, उग्रतपसायुक्तं doing severe penance, सत्यवादिनम् to the truthful तं महर्षिम् to that great sage, काश्यपः Kasyapa, ब्रह्माणमिव as he would speak to Brahma, प्रत्युवाच thus replied.
Selfpossessed Rama replied to the truthful ascetic who had performed intense penance. Just as Kasyapa would address Lord Brahma: