Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 75: The History of the Bows of Lord Śiva and Lord Viṣṇu
Text 1.75.4

तदहं ते बलं दृष्ट्वा धनुषोऽस्य प्रपूरणे।
द्वन्द्वयुद्धं प्रदास्यामि वीर्यश्लाघ्यस्य राघव॥

tad ahaṁ te balaṁ dṛṣṭvā dhanuṣo ’sya prapūraṇe
dvandva-yuddhaṁ
pradāsyāmi vīrya-ślāghyasya rāghava

tat = and then; aham = I; te balam dṛṣṭvā = seeing Your strength; dhanuṣaḥ asya prapūraṇe = in stringing this bow; dvandva-yuddham pradāsyāmi = will offer You a one to one duel; vīrya-ślāghyasya = who are famous for Your prowess; rāghava = O Rāghava.

And then, seeing Your strength in stringing this bow, I will offer You, who are famous for Your prowess, a one to one duel, O Rāghava!