Valmiki Ramayana Yuddha Kanda Sarga 21 Shloka 11

तदा then, तत्र there, नयज्ञः one having political foresight, धर्मवत्सलः lover of dharma, रामः Rama, त्रीरात्रोषितः spent three nights, सरितांपतिम् Lord of rivers, सागरम् the ocean, उपासत waiting upon.

Rama, a lover of dharma, who had political foresight, spent three nights waiting upon the ocean, the Lord of rivers.