Mahabharata 9.39.23

सोऽस्मिंस्तीर्थवरे राजन्सरस्वत्याः समाहितःनियमैश्चोपवासैश्च कर्शयन्देहमात्मनः

so'smiṃstīrthavare rājansarasvatyāḥ samāhitaḥniyamaiścopavāsaiśca karśayandehamātmanaḥ

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