Valmiki Ramayana Bala Kanda Sarga 57 Shloka 9
Original Shlokaइति निश्चित्य मनसा भूय एव महातपा:। तपश्चकार काकुत्स्थ परमं परमात्मवान्।।1.57.9।।
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काकुत्स्थ O Rama, महातपाः (महायशा:) highly famous, परमात्मवान् great intellectual, इति thus, मनसा with his mind, निश्चित्य having decided, भूय: एव once again, परमम् greater, तप: austerities, चकार performed.
"O Descendant of Kakustha (Rama) this celebrated intellectual having decided in his mind once again performed greater austerities.