Mbh 1.211.2a

“Vaisampayana said, ‘Hearing these words of Yudhishthira, Narada replied, ‘O son of Pritha, listen with thy brothers to me as I recite this old story, O Yudhishthira, exactly as everything happened. In olden days, a mighty Daitya named Nikumbha, endued with great energy and strength was born in the race of the great Asura, Hiranyakasipu. Unto this Nikumbha, were born two sons called Sunda and Upasunda. Both of them were mighty Asuras endued with great energy and terrible prowess. The brothers were both fierce and possessed of wicked hearts. And those Daityas were both of the same resolution, and ever engaged in achieving the same tasks and ends. They were ever sharers with each other in happiness as well as in woe. Each speaking and doing what was agreeable to the other, the brothers never were unless they were together, and never went anywhere unless together. Of exactly the same disposition and habits, they seemed to be one individual divided into two parts. Endued with great energy and ever of the same resolution in everything they undertook, the brothers gradually grew up. Always entertaining the same purpose, desirous of subjugating the three worlds, the brothers, after due initiation, went to the mountains of Vindhya. And severe were the ascetic penances they performed there. Exhausted with hunger and thirst, with matted locks on their heads and attired in barks of trees, they acquired sufficient ascetic merit at length. Besmearing themselves with dirt from head to foot, living upon air alone, standing on their toes, they threw pieces of the flesh of their bodies into the fire. Their arms upraised, and eye fixed, long was the period for which they observed their vows. And during the course of their ascetic penances, a wonderful incident occurred there. For the mountains of Vindhya, heated for a long course of years by the power of their ascetic austerities, began to emit vapour from every part of their bodies.