दशरात्रस् तु यज्ञश्च तस्मिन्रामेण राक्षसौ।
हन्तव्यौ विघ्नकर्तारौ मम यज्ञस्य वैरिणौ।
अहं ते प्रतिजानामि हतौ तौ विद्धि राक्षसौ॥
daśa-rātras tu yajñaś ca tasmin rāmeṇa rākṣasau
hantavyau vighna-kartārau mama yajñasya vairiṇau
ahaṁ te pratijānāmi hatau tau viddhi rākṣasau
daśa-rātraḥ tu = for ten nights; yajñaḥ ca = the sacrifice is; tasmin = within that time; rāmeṇa = Rāma; rākṣasau = the two rākṣasas; hantavyau = should kill; vighna-kartārau = who obstruct; mama = to my; yajñasya = sacrifice; vairiṇau = and are hostile; aham = I; te = you; pratijānāmi = declare that; hatau = are already killed; tau = those; viddhi = should know that; rākṣasau = two rākṣasas.
The sacrifice is for ten nights. Within that time, Rāma should kill those two rākṣasas who obstruct and are hostile to my sacrifice. I declare that you should know that those two rākṣasas are already killed!
Killing those rākṣasas is an easy work for Rāma and so Viśvāmitra speaks as if they have already been killed.