Valmiki Ramayana Ayodhya Kanda Sarga 46 Shloka 16
Original Shlokaजाग्रतो ह्येव तां रात्रिं सौमित्रेरुदितो रविः। सूतस्य तमसातीरे रामस्य ब्रुवतो गुणान्।।2.46.16।।
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तमसातीरे on the bank of river Tamasa, रामस्य Rama's, गुणान् virtues, सूतस्य (in) the chrioteer's (presence), ब्रुवतः telling, सौमित्रेः Lakshmana, तां रात्रिम् that night, जाग्रतोह्येव by keeping awake, रविः the Sun, उदितः arose.
Lakshmana continued to describe Rama's virtues to the charioteer, keeping awake that entire night on the bank of Tamasa until the Sun rose.