Mahabharata 10.12.29

ब्रह्मचर्यं महद्घोरं चीर्त्वा द्वादशवार्षिकम्हिमवत्पार्श्वमभ्येत्य यो मया तपसार्चितः

brahmacaryaṃ mahadghoraṃ cīrtvā dvādaśavārṣikamhimavatpārśvamabhyetya yo mayā tapasārcitaḥ

Our plain-language meaning of this verse is waiting for scholar review.