Mbh 3.47.1a

Vaisampayana said, “One day, the great Rishi Lomasa in course of his wanderings, went to the abode of Indra, desirous of beholding the lord of the celestials. And the great Muni, having approached the chief of the gods, bowed to him respectfully. And he beheld the son of Pandu occupying half of the seat of Vasava. And worshipped by the great Rishis, that foremost of Brahmanas sat on an excellent seat at the desire of Sakra. And beholding Arjuna seated on Indra’s seat, the Rishi began to think as to how Arjuna who was a Kshatriya had attained to the seat of Sakra himself. What acts of merit had been performed by him and what regions, had been conquered by him (by ascetic merit), that he had obtained a seat that was worshipped by the gods themselves? And as the Rishi was employed with these thoughts, Sakra, the slayer of Vritra, came to know of them. And having known them, the lord of Sachi addressed Lomasa with a smile and said, ‘Listen, O Brahmarshi, about what is now passing in thy mind. This one is no mortal though he hath taken his birth among men. O great Rishi, the mighty-armed hero is even my son born of Kunti. He hath come hither, in order to acquire weapons for some purpose. Alas! dost thou not recognise him as an ancient Rishi of the highest merit? Listen to me, O Brahamana, as I tell thee who is and why he hath come to me. Those ancient and excellent Rishis who were known by the names of Nara and Narayana are, know, O Brahmana, none else than Hrishikesa and Dhananjaya. And those Rishis, celebrated throughout the three worlds, and known by the names of Nara and Narayana have, for the accomplishment of a certain purpose, been born on earth--for the acquisition of virtue. That sacred asylum which even gods and illustrious Rishis are not competent to behold, and which is known throughout the world by the name of Vadari, and situate by the source of the Ganga, which is worshipped by the Siddhas and the Charanas, was the abode, O Brahmana, of Vishnu and Jishnu.