Mahabharata 13.107.81

उपवासं च कुर्वीत स्नातः शुचिरलंकृतःपर्वकालेषु सर्वेषु ब्रह्मचारी सदा भवेत्

upavāsaṃ ca kurvīta snātaḥ śuciralaṃkṛtaḥparvakāleṣu sarveṣu brahmacārī sadā bhavet

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