Valmiki Ramayana Ayodhya Kanda Sarga 61 Shloka 19

अत्यमर्षण: highly determined, रामः Rama, इमाम् this, धर्षणाम् indignity, न सङ्गच्छेत् will not suffer, क्रुद्ध: if angered, सः he, शितैः with sharp, सरैः with arrows, मन्दरमपि even mount Mandara, दारयेत् हि will split open.

Rama, highly determined will not suffer this indignity. If enraged, he can split open even mount Mandara with his sharp arrows.