Valmiki Ramayana Bala Kanda Sarga 38 Shloka 1
Original Shlokaतां कथां कौशिको रामे निवेद्य कुशिकात्मज:। पुनरेवापरं वाक्यं काकुत्स्थ मिदमब्रवीत्।।1.38.1।।
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कुशिकात्मज: the offspring of Kausika, कौशिक: Visvamitra, तां कथाम् that story, रामे to Rama, निवेद्य having related, पुनरेव again, इदम् this, (अपरं) वाक्यम् words, काकुत्स्थम् addressing Rama, अब्रवीत् had spoken.
Viswamitra, an offspring of Kusika having related the story (of Karthikeya) to the son of the Kakusthas (Rama) said again. Emperor Sagara performs austerities and a sacrifice for progeny.