Canto 2 -
Ayodhyā-kāṇḍa
Chapter 58: Sumantra Conveys the Message of Rāma and Lakṣmaṇa
Text 2.58.20
कुमारे भरते वृत्तिर्वर्तितव्या च राजवत्।
अर्थज्येष्ठा हि राजानो राजधर्ममनुस्मर॥
kumāre bharate vṛttir vartitavyā ca rājavat
artha-jyeṣṭhā hi rājāno rāja-dharmam anusmara
kumāre = the young; bharate = Bharata; vṛttiḥ vartitavyā ca = serve; rājavat = as you would deal with a king; artha-jyeṣṭhāḥ hi = are superior due to their prosperity; rājānaḥ = kings; rāja-dharmam = your duty to the king; anusmara = so remember.
Serve the young Bharata as you would deal with a king. Kings are superior due to their prosperity. So remember your duty to the king.
Kings are superior due to their prosperity, not due to their age.