Mbh 1.61.6a

‘The sons of Kunti reached the town of Varanavata and lived there with their mother. And, agreeably to the command of Dhritarashtra, those illustrious slayers of all enemies lived in the palace of lac, while in that town. And they lived in that place for one year, protecting themselves from Purochana very wakefully. And causing a subterranean passage to be constructed, acting according to the directions of Vidura, they set fire to that house of lac and burnt Purochana (their enemy and the spy of Duryodhana) to death. Those slayers of all enemies, anxious with fear, then fled with their mother. In the woods beside a fountain they saw a Rakshasa. But, alarmed at the risk they ran of exposure by such an act the Pandavas fled in the darkness, out of fear from the sons of Dhritarashtra. It was here that Bhima gained Hidimva (the sister of the Rakshasa he slew) for a wife, and it was of her that Ghatotkacha was born. Then the Pandavas, of rigid vows, and conversant with the Vedas wended to a town of the name of Ekachakra and dwelt there in the guise of Brahmacharins. And those bulls among men dwelt in that town in the house of a Brahmana for some time, with temperance and abstinence. And it was here that Bhima of mighty arms came upon a hungry and mighty and man-eating Rakshasa of the name of Vaka. And Bhima, the son of Pandu, that tiger among men, slew him speedily with the strength of his arms and made the citizens safe and free from fear. Then they heard of Krishna (the princess of Panchala) having become disposed to select a husband from among the assembled princes. And, hearing of it, they went to Panchala, and there they obtained the maiden. And having obtained Draupadi (as their common wife) they then dwelt there for a year. And after they became known, those chastisers of all enemies went back to Hastinapura.