Valmiki Ramayana Bala Kanda Sarga 70 Shloka 22
Original Shlokaतमिक्ष्वाकुमयोध्यायां राजानं विद्धि पूर्वकम्। इक्ष्वाकोस्तु सुतश्श्रीमान् कुक्षिरित्येव विश्रुत:।।1.70.22।।
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तम् इक्ष्वाकुम् him as Ikshvaku, अयोध्यायाम् in the city of Ayodhya, पूर्वकम् राजानम् ancestral king, विद्धि be informed, श्रीमान् the glorious, कुक्षिरित्येव known as Kukshi, विश्रुत: wellknown, इक्ष्वाको: Ikshvaku's, सुत: son(was born).
It may be noted that Ikshvaku was the first ancestral king of Ayodhya whose son was the wellknown, glorious Kukshi.