Mahabharata 12.311.25

गुरवे दक्षिणां दत्त्वा समावृत्तो महामुनिःउग्रं तपः समारेभे ब्रह्मचारी समाहितः

gurave dakṣiṇāṃ dattvā samāvṛtto mahāmuniḥugraṃ tapaḥ samārebhe brahmacārī samāhitaḥ

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