Valmiki Ramayana Ayodhya Kanda Sarga 19 Shloka 23

अहम् I, अत्र भवता by this venerable (father), अनुक्तोपि even without being told, भवत्याः your, वचनात् by your word, इह now, चतुर्दश वर्षाणि fourteen years, विजने solitary, वने in the forest, वत्स्यामि will live.

Though this has not been said by my respectable father himself, I shall live in the forlorn forest for fourteen years in accordance with your word.