Valmiki Ramayana Ayodhya Kanda Sarga 36 Shloka 16
Original Shlokaवैव वंशे सगरो ज्येष्ठं पुत्रमुपारुधत्। असमञ्ज इति ख्यातं तथायं गन्तुमर्हति।।2.36.16।।
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तव in your, वंशे एव dynasty itself, सगरः Sagara, असमञ्जः इति as Asamanjasa, ख्यातम् wellknown, ज्येष्ठपुत्रम् eldest son, उपारुधत् was prevented (from assuming the kingdom), अयम् this Rama also, तथा in the same way, गन्तुम् to go, अर्हति is worthy of.
In your own dynasty king Sagara prevented his wellknown eldest son Asamanjasa (from enjoying the kingdom). Rama also should depart in the same manner.