Valmiki Ramayana Yuddha Kanda Sarga 21 Shloka 25

एवम् in that manner, उक्त्वा having spoken, धनुष्पाणिः bows etc. क्रोधविस्फारितेक्षणः with flaming red eyes, रामः Rama, ज्वलन् burning, युगान्तानगिरिव like the flame at the end of the universe, दुर्धर्षः unassailable, बभूव seemed.

Having spoken like that, Rama with his flaming red eyes seemed like the flame at the end of the universe and unassailable.