Ramayana
अहं तु हिमवत्पृष्ठं गतो धर्ममुपासितुम् । रौद्रं व्रत्तं समास्थाय नियतो नियतेन्द्रियः ॥ 7-13-21 ॥
'But I went to the heights of the Himalaya to practice dharma, and undertaking a fierce vow, self-controlled and with senses restrained, I dwelt there.'
english translation