Valmiki Ramayana Bala Kanda Sarga 30 Shloka 4

राघवौ Rama and Lakshmana, युवाम् both of you, अद्यप्रभृति from today onwards, षड्रात्रम् six nights, रक्षतम् you may protect, एष: मुनि: this sage Visvamitra, दीक्षाम् initiation ceremony, गत: has entered, मौनित्वं च strict silence also, गमिष्यति will attain.

"O sons of Raghu's lineage protect the sacrifice for six nights from today. With the ceremoney initiated, the sage would observe silence said the inmates".