Mahabharata 3.93.14

3.93.14

brāhmaṇāstatra śataśaḥ samājagmustapodhanāḥ |
cāturmāsyenāyajanta ārṣeṇa vidhinā tadā || 14 ||

In that region is the hill called Gayasira, as well as the delightful river called Mahanadi, with fine banks graced by bushes of canes. On that celestial hill of holy peaks is a sacred tirtha called Brahmasara which is much adored by ascetics. There on the banks of that lake had dwelt of yore the eternal god himself of justice, and it was thither that the illustrious Rishi Agastya had repaired to behold that deity. It is from that lake that all the rivers take their rise and there in that tirtha, Mahadeva the wielder of the Pinaka, is present for aye. Arriving at that spot, the heroic sons of Pandu practised the vow that is known by the name of the Chaturmasya according to all the rites and ordinances of the great sacrifice called Rishiyajna. It is there that that mighty tree called the Eternal banian stands. Any sacrifice performed there produces merit that is eternal. In that sacrificial platform of the gods producing eternal merit, the Pandavas began to fast with concentrated souls. And there came unto them Brahmanas by hundreds endued with wealth of asceticism. And those Brahmanas also all performed the Chaturmasya sacrifice according to the rites inculcated by the Rishis. And there in that tirtha, those Brahmanas old in knowledge and ascetic merit and fully versed in the Vedas, that constituted the court of the illustrious sons of Pandu, talked in their presence upon various subject of sacred import.