Valmiki Ramayana Sundara Kanda Sarga 51 Shloka 31

अहम् I, एकोऽपि all alone also, सवाजिरथकुञ्जराम् full of horses, chariots and elephants, लङ्काम् Lanka, नाशयितुम् to destroy, कामम् indeed, शक्तः खलु I have the energy, एषः this, तु indeed, निश्चयः resolution, न not.

" Alone, I can destroy this entire Lanka teeming with horses, chariots and elephants. Indeed I have the energy but not the mandate of Sri Rama.